Expand the IDE controller in device manager and report back. You should see the primary and secondary channels, and something like "standard dual channel PCI IDE controller" This is the actual controller driver should show with the MS driver.
You have a VIA chipset and you may have installed the wrong IDE controller driver for Win XP. So if the controller shows up as a VIA IDE controller instead of the above, you have 2 choices. Either revert to the default MS driver or go find the updated VIA drivers. It used to be called "VIA 4in1", and that's what came on the Gateway systems. Some of those boards work better with the VIA IDE driver, some work better with the MS driver.
If you need help switching to the MS driver, just ask. But it's in the list in the wizard for updating the drivers.