If this is a VISTA to XP move then you should at least prepare all the drivers first before even erasing Vista. If you have problems with the Gateway website, I suggest you call them and ask them any alternative. You can also run PC Wizard in Vista to know what drivers you need. From there you need to hunt down each and every driver.
Here's an example of a successful downgrade but this involved many hours of hunting for drivers.
http://www.techsupportforum.com/hard...facturers.html