The setup programs that you will download from nVidia are often designed to be run from within an existing XP installation, and so will not be directly helpful when clean installing XP.
A lot depends on whether or not you have a floppy drive (I suspect not). If you do, then you should try and locate a floppy drive image containing the drivers, and copy this to a blank floppy, then hit F6 during setup to install the drivers.
Otherwise, there's just one solution.
First, you should get the correct drivers software for your motherboard, and unpack this software using WinRAR (after you install WinRAR, reboot - then right-click on the setup .exe, and unpack to a folder in a convenient location) ; inside this folder, you should be able to locate SATA drivers for XP.
You would then need to create a personalised XP setup CD containing these drivers using software called
nLite -- I am told that this is relatively easy, and of course you will also need a blank CD and CD burning software.
I am not an expert in using nLite, but if you ask again here, I'm sure people will be able to help
