Time for Your XP Install
After all of that prep, installing XP over Vista is, in itself, not too difficult: Boot with your XP installation disc and install XP, overwriting Vista. And just make sure to select the partition that Vista is on and follow the prompts.
As I've said, there's not a lot you can do about migrating your applications back. If you were using two separate PCs, you could use Windows Easy Transfer or a similarly capable commercial product. I didn't consider that option, because
The solution is to reinstall your apps--which
Am I happy I moved back to XP? Very much so. The time I save by using Outlook Express
If you'd like to try Vista before removing XP, or if you're using Vista and would like to take a stroll down memory lane to see just how efficient the older OS is, download VMware Server or Virtual PC 2007 for free and try them in a virtual machine.