@LewisRaz, Your Athlon XP setup is based on the Asus A7N8X Deluxe, yes? Is yours a v2.0 (Gold) board, or an earlier revision? What CPU are you running, and which driver versions (and which OS, XP SP3 I assume?). I've got an A7N8X Deluxe v2.0 coming today and am still deciding what CPU to use but want to start compiling the drivers I'll need (and work out which GPU to use, I've got a decent choice these days!).
I've got the following AGP cards "available" (as in, not currently in a system):
3DFx Voodoo 3 3000 16MB
ATi Radeon 9200SE 128MB
ATi Radeon 9800 XXL 128MB
ATi Radeon 9800XT 256MB (AGP Pro, flashed Apple G5 card, so needs no external power)
nVidia Geforce 2 MX200 64MB
nVidia Geforce 2 MX400 64MB
nVidia Geforce 2 Pro 64MB
nVidia Geforce 2 Titanium 64MB (Thanks Lewis!)
nVidia Geforce 4 MX460 64MB
nVidia Geforce 4 Ti4200 128MB
nVidia Geforce 6 6800XT 128MB
nVidia Geforce 7 7900GS 512MB
PowerVR Kyro II (Prophet 4500) 64MB
As you can see, a decent list!
Yep, it didn't like the USB card. Removed it and have just been playing NFS3 using Glide for an hour, no problems at all. Looks like I got lucky, but need to look into a different USB card or driver perhaps... hope it's not NUSB-related, as I really would like to be able to use flash storage devices easily on Win98. But overall, quite chuffed!
What's the rest of the system? My Super Socket 7 system (K6-III 450 @ 550) tanked in performance with a Belkin (NEC chipset) USB 2.0 card installed (even if disabled in Device Manager). With a VIA chipset USB2.0 card I was getting roughly 95% of the performance I attained without any additional USB cards (the motherboard has USB 1.1 on-board). Much-like different sound cards can have different performance impacts on older systems, so too can other devices and peripherals!