No, there is no way to avoid purchasing another copy. You're using it on TWO computers, right? You need two copies.
You don't ask if someone can make a copy of your car so that you can give it to your girlfriend, do you?
The idea is the same.
You use the product, it has value; if you need two, you're gonna have to buy two.
If you look hard enough, at places that aren't the TFP (where we tend not to support piracy - though, we're split on the whole mp3 thing), you will find step by step instructions on how to rip off microsoft and use the same copy on multiple computers.
However, it's not exactly easy to steal XP. So, I hope you've got patience, and a fair amount of computer skills.
Or, go to
buy one here.
The third one down is Win XP Pro, for $143. In order to satisfy some inane "hardware purchase requirement" MS has, newegg.com will give you a free power cable. Well, you have to buy the power cable for $5. But, they give you $5 off when you order the OS. See how that works out?
$143 isn't that bad for a full version of XP Pro.
I can't fathom why the fuck MS would force someone to buy hardware with the OS. To me, that encourages the user to say "screw MS, I'll find a goddamn way to steal it, if you are going to make it difficult to buy." Ideas on that one?