Also, Vaios generally don't come with all the applications on disk. Make sure to follow the process to make your backup disks BEFORE you wipe and install XP. This is really important because you'll need your drivers for stuff like your trackpad and your bluetooth, and it's a nightmare trying to download them online.

Also, I've heard you can download and install Windows 7 for free right now as it's in beta. This might be an option also. I haven't tried it, but I've heard really, really good things.