Sorry I didn't see that you were downgrading to XP, and thought you were just reloading. Dweez is obviously right in that definitely some of your Vista drivers will not work with XP so if you were to use an auto back-up prog you should save the drivers individually.
I actually use Belarc and not Everest but I would suppose they are the same, but a solution to your problem maybe something like "Driver Detective". I originally thought that it was spyware and advised against it but after some research I realised it was kosher and nothing to be afraid of -
read here.
You will have to make sure that you have your network card working ok so download the XP driver for that before you reload, then software like DD will seek all your other drivers for you. It is an easy way to at least get your machine roughly to the way you want it, and then you can manually configure the fine tuning.