wclem wrote:I honestly never researched if XP will recognize SATA or if the PCI-e video cards would even have drivers for XP or even earlier Windows versions.
Figure, Vista came out in 2007, and then Windows 7 in 2009. The Core line started in 2006-ish, though many of the popular ones we'd think of are more like '07 or '08 (Q6600, E8500 for instance). Still, that puts them in a time period where XP support was still important, since it was still the dominant Windows version.
That being said, you do occasionally run into things that didn't support earlier version of Windows, though I've only really seen it with a few laptops. Usually it's stuff like sound cards with no legacy drivers, since that was a major thing that changed between XP and Vista.
If you plan to use the same hardware for 98 though, then sticking with AGP/etc is probably better. PCIe was not officially supported in that. While there are apparently some cards and things that work, it'd likely take a bit more effort to put together.