I too have a 9800 Pro and mostly play BF2 at 1280x1024 medium settings with no issues with frame rates. Paired with a P4 2.8 Northwood and 2GB of PC3200 DDR the machine has served me well for 2.5 years. I may replace the system with a Conroe based platform in the autumn.
If you want to replace a 9800 Pro look at a 7800GS (the Gainward 7800GS+ is actually a 7800GT GPU if you can source one), that should extend your AGP based system an extra 12 months or so. 2GB of RAM will help too.
If you want to replace a 9800 Pro look at a 7800GS (the Gainward 7800GS+ is actually a 7800GT GPU if you can source one), that should extend your AGP based system an extra 12 months or so. 2GB of RAM will help too.