Thanks, but the first article really doesn't seem to apply to my situation. It describes how to drop back to XP after upgrading from XP to Vista. What I'm trying to do is remove / uninstall Vista without damaging XP. I have XP installed on one hard drive, Vista installed on the other, in a dual-boot configuration - so XP is available right now.
Is there anything that should be done (can be done?) to remove Vista besides just reformatting the drive it's installed on? (The second article seems to be talking about the aftermath of removing Vista by reformatting its partition.) As I said, I would really prefer not to damage the installed copy of XP.