BFG GeForce 6800 GS OC 256MB GDDR3 AGP 8x DVI VGA TV Out Video Card BFGR68256GSOC at TigerDirect.com
That is the card I have, I can run most games at mid-high settings. Highest games I've tried to run on it are GRAW, HL2, 1701AD (anno 1701).
I am pleased with it, and it is one of the best you can get for AGP, or it was when I purchased it, (last year).
Here is a list of some more, the ones listed first are better( by specs), then the ones below: All are AGP.
XFX GeForce 7950 GT 512MB GDDR3 AGP 8x DL Dual DVI HDTV Video Card PVT71AYDF3 at TigerDirect.com
XFX GeForce 7900 GS 256MB DDR3 AGP 8x Dual DVI HDTV Video Card PVT71KUDF3 at TigerDirect.com
EVGA GeForce 7800 GS CO 256MB GDDR3 AGP 8x DVI VGA TV Out Video Card 256-A8-N506-AX at TigerDirect.com
BFG GeForce 7800 GS 256MB GDDR3 AGP 8x DVI VGA TV Out Video Card BFGR78256GSOC at TigerDirect.com
BFG GeForce 6800 GS OC 256MB GDDR3 AGP 8x DVI VGA TV Out Video Card BFGR68256GSOC at TigerDirect.com
I have the last one. Things that I don't know, are your budget, and your power supply. As it will depend on that mostly. All of these will blow the GeForce 4 out of the water, and they will also perform several times better then the 9800.
The one question is what is your operating system? Windows XP Home? Pro? etc.
and how much ram do you have? If you don't have 1GB of ram, then it is probably that your system ram is holding you back as well. If it seems slow and laggy then it can be either your CPU, GPU, or system Ram, (for most cases). GPU was explained above by Vernong1992.
Look at those and choose one you like, look at newegg and see if they have it for cheaper, then post back here with the one you think you want and we can comment on it. Depending on budget, I would go with one of the top three. (be advised that I will mostly only by BFG, XFX, or EVGA, so that is all that is listed).
EDIT -- That card won't work with your system. The 8600GTS you posted. THis is because it is a PCI-e x16 card, and you only have PCI and AGP.
PCI worse then AGP worse then PCI-e.
387Mhz, sounds right for the Radeon 9800,
Radeonâ„¢ 9800 Series
The cards I listed all are above that spec, however the one I have, the last one listed, is just a little over.