NOTE: Windows XP 32-bit will only be able to recognize up to 3GB of memory.
Recommend going to Device Manager while Vista is installed and taking screenshots of everything installed (Alt+Print Screen). Save screenshots of installed devices to another drive off of your Gateway to be downgraded to XP.
VERY IMPORTANT (don't skip this step): Use Gateway application to burn backup DVDs of software on second partition. Three DVDs total. We'll end up using the AppDrv1 DVD later for the TouchPad software and other stuff.
Slipstream SATA drivers into Windows XP using nLite (it's not too tough):
Get a copy of Windows XP
Download SATA driver from somwhere
Download and Install nLite (http://www.nliteos.com/download.html)
Launch nLite and click Next
Locate copy of Windows XP
Create a folder for new installation and point to it as prompted, click Next twice
Select Drivers and Bootable ISO
For driver, select single driver and find the iaAHCI.inf in the SATA Driver folder
Select Intel (R) ICH8M-E/M SATA AHCI Controller and click OK, click Next, OK to start the process
Burn directly to a disc
Boot Gateway with new XP disc and go through the setup process.
Upon bootup, install remaining drivers manually:
Insert the AppDrv1 DVD you made prior to reimaging your machine and go to the D:\DRV directory. Try installing all you can from here first. Links below are for whatever may not work from this DVD. I don't think the Sigmatel Audio will work so you'll use the link below for that.