insufficient info. you need to know your motherboard make and model, which you can get from the gateway site (or running e.g. belarc advisor). Then visit the motherboard m/f site for drivers for the O.S. you have (also incompletely specified). How on earth you think your details percolate automatically over the internet, I have no idea.
For all I know, everything you want could be on the Gatway site.
At a guess, you bought a Gateway with Vista ready-installed, and want to revert to XP ? If so, a direct request to Gateway ought to be helpful, either technical assistance or even the sales channel might help.