Re-install Windows XP

When you buy a computer that isn't Apple, 99% of the time it's going to come with some version of Windows, whether it be XP, Vista, and soon, Windows 7. Sometimes your computer will come with a few CDs, one of which might be the Windows re-install disc, in case you have to re-install Windows. Truthfully, if you use Windows for long enough, sooner or later you're going to need to reinstall it. Here's the sad part - a LOT of computer manufactures like to save a small insignificant amount of money when shipping your computer and refuse to give you a Windows reinstall disc (Dell being the big exception I'm aware of). Although a lot of computer vendors will give you one if you pay extra for it. Instead of going on a rant about how that is ludicrous, I'm going to explain what your options are if you need to re-install Windows and don't have a Windows reinstallation disc.

Legalities
First, though, a caveat. Remember I said that having to pay extra for the installation disc for an operating system you already own a license for is ludicrous? It gets worse. Because Windows discs are copyrighted material, if you were to back up or make a copy of one of those discs, you're technically breaking copyright and breaking the law. I say technically, because that's what the Digital Millennium Copyright Act says. However, when you get a computer with Windows or buy a copy of Windows from the store, what you're spending money on is the license to use Windows on one computer. So although copying the Windows disc is breaking the law under the DMCA, Microsoft isn't losing money because what you purchased was the license (that little product key that is stuck on the case of your computer). With that out of the way, I'll get into the meat of things - just be aware that depending on how you interpret copyright law, you are probably breaking copyright.

Okay, so you've got a computer, but no Windows disc, and you need to re-install.
The first step is to figure out who made your computer (HP, Dell, IBM, Gateway, etc), what version of Windows you've got (should be on the same sticker as your product key), and if possible, try to find your Windows Product Key (most likely stuck to the case of your computer). For example, you may have a computer from Dell that has a copy of Windows XP Home Edition. The vendor name (in this case, Dell) is important because of a thing called a BIOS lock. A BIOS lock is when a copy of Windows XP is customized to only work on a particular brand of computer. In this example, if you have a Dell and you insert a Windows disc that was designed for a Gateway, you're going to get a message on the screen that "This software only works on a Gateway" and your computer restarts. Welcome to more ludicrous-ness.

Aside: The only justification for this is a technique that some vendors use to customize their Windows installation discs. When you install a Dell customized version of Windows on a Dell computer, for example, you won't be prompted for your Windows Product Key. This is handy, because if you've lost your product key for somehow, you should be able to complete the install anyway (although you probably won't have any way to prove you've got a legal license when the men in suits show up at your door). On top of that...it's theoretically possible to use this trick to install XP on a Dell computer (again, for example), that only has Windows 2000. You don't need a valid product key because Dell's disc doesn't ask for one. Now this is very illegal and you should not do this, because this time you're using Windows without paying for a license. This is stealing, don't do it, blahdeeblah. Just....don't. We good with that?

So you've got your brand of computer, you know which version of Windows you're using (XP Home, XP Pro, Vista, etc), and you have your product key, just in case. Now comes the tricky part. We're going to have to do some searching on the internet for torrents of the Windows disc you need. Yes, again, this is technically piracy and violating copyright, because the contents of the disc are copyrighted. So, if you do this, you ARE breaking the law. However, again, what you paid for when you bought your computer/bought a retail copy of Windows, was the license, so the disc really has no monetary value. Anyway, I'm not going to delve into how to use Bit Torrent. What I am going to tell you is what to look for. Assuming you're doing a full install and not an install-in-place (more on that later), you'll be searching for something like "Dell Windows XP Home" or "HP Windows XP Pro." You need to specify the brand of your computer and which version of Windows you need. If you're doing a full install, it doesn't really matter what service packs are bundled with the torrent (denoted as SP2, SP3, etc). If you do a full install, you can update to the latest service pack later. The important thing is to get a torrent of the Windows disc you need, burn that to a CD (or DVD, if it's for Vista) and see if it works.

OEM
As you're looking for the version you need, you will probably come across versions referred to as OEM. OEMs are discs made for computer manufacturers, but if they don't say a computer brand, then they're not the BIOS locked versions. What this means is if you have a generic computer, or you're having a hard time finding a disc for your brand of computer, it might not need a brand-specific version of Windows. For example, I've had to work on a computer that wasn't manufactured by a big-name brand, and I couldn't find a disc for it. But I downloaded the OEM version and it worked just fine. So something good to know.

Install In Place
There's another trick you can do with a Windows CD, provided you're careful. Most of the time, when you re-install XP with a disc that didn't specifically come with your computer, your only option will to perform a new, full installation. However, if you can find a Windows disc that is the same brand, same version and same service pack, you might be able to perform an install in place. Basically, an install in place takes your currently installed Windows on your computer and replaces all the original Windows files with their original "factory default" files. If all goes well, this effectively repairs your broken Windows instance and usually lets you continue to use your computer as if nothing had happened - don't need to re-install drivers, software, or files. Just make sure to perform a backup, if you can, before you proceed, just in case. I cannot stress how useful this trick can be if you're trying to repair a copy of Windows that has crashed. More on how to do an install in place here

The Installation
After you've got your Windows disc burned to a CD or a DVD, follow your computer's instructions for booting a computer using a CD. If the torrent was good, you should be presented with the Windows installation. Just proceed through the installation (more on that here). Depending on your brand of computer and the disc you're using, you might be asked for a product key during the installation and you might be asked to activate Windows once the install is done. If you try to activate Windows with the product key on your computer's case and it fails, it is most likely the wrong version of Windows for the product key. If you are sure everything's okay, you can try to contact Microsoft and get a new activation code, but double-check that you've got the correct Windows version - if you have a version other than what the product key was designed for, Microsoft isn't going to help you.

And if you're using a cracked version of Windows so you don't have to activate or have a product code, shame on you and may your computer get infected with the worst kinds of nasties.

Eventually, if all went well, the install should complete, but you'll most likely need to get drivers for everything, such as video, network, etc. Depending on where your computer came from, this could be easy (like with a big brand name) or a hassle - try the your computer manufacturer's website (and see if your computer has a service code or tag, or a serial number). Unless you did an install-in-place, you'll have a fresh computer without any programs or files, so you'll have to re-install everything you need. But you'll have a nice fresh installation of Windows. Enjoy. :)