9800 XT running slow in games

I got a 9800 XT today to replace my 8500LE, but I've got something that is rather confusing me and is actually starting to annoy me.

I've been told my system spec should be able to handle the card without a problem, but I'm positive this isn't running as fast as it should be (and my friends also agree). The reason being is:

In UT2004, I have settings at max for detail and run the game at 1280x1024 (no filtering modes though in the drivers or game) and my frame acts just the same as it does with my 8500LE in low detail and at 1024x768 (almost all onslaught maps get a frame of 10-40). This can't be right for a card that is way more powerful than a 8500LE. I'm thinking it's a setting somewhere as lowering the resolution and detail settings only gains me about 5 FPS average.

The same thing also happens in Medal of Honor (full details causes my frame to drop to about 30-40 no way for this old game!) and Half-Life 2 acts the same.

I'm using the latest Omega drivers, latest VIA chipset drivers, fast write off, using 8X AGP mode and motherboard BIOS is fully up-to-date.

My system spec is as follows:

Asus A7V600-X motherboard
AMD Athlon XP 2400+ (T-bred core, 2GHZ)
1.28GB PC2700 Kingston DDR memory
Sound Blaster Audigy 2 ZS sound card
Games running off a Seagate Barracuda 80GB 7200RPM 8MB Cache SATA drive
Tagan 480W PSU
Running Windows 2000 Professional SP4 (fully up-to-date)

I have ran 3DMark03 and got a score of 6083, tried running 3DMark05 but the CPU tests keep crashing (program will just randomly crash, no error message, just close).

I'm going to download Prime and run it on my CPU thru the night (memory has been fully tested with memtest, no problems).

Any ideas?