I don't use ATI cards myself, but I'm in the 9800 Pro camp or nothing. If I'm going to use an ATI card it will be that one and no others. It's the best card ATI ever made.

Depends on what OS you are planning on using it with, but in the early 2000s ATI was really killing it.

Both the Radeon 8500 and 9800 Pro are very good cards (I myself have an 8500LE, 9800 Pro and an X800XT AGP). The R400 is also an awesome series, the last and fastest graphics cards with proper W98 drivers, but also fast in early-to-mid XP, up until about 2006. In later games the absence of SM3.0 support can spoil the experience. For that the R500 was very competitive as well. I often see X1950 Pros for a decent price. The Rage6/Radeon DDR was also a decent Geforce 2 competitor on the late drivers.

For budget builds, Radeon 7200 64MB (basically a Radeon DDR) Radeon 9100 (also essentially an 8500LE), 9600 Pro/XT and X700 are generally cheap. I also have good experience with the RV410 based 128bit/256MB X1050 (esentially an X700 Pro).

Where they can be lacking is some 90's legacy support which they generally dropped before Nvidia.

I think most people should stay away from 8500 though. Unless interested in Truform. They are the only hardware accelerated Truform chips. Though frankly Truform is very limited in value. You basically need to do side by side screenshot comparisons to see the difference.

Otherwise they seem like buggy chips. The antialiasing is slow and really glitchy as to whether it will work or even stay enabled. Texture filtering is terrible compared to Radeon R300 and newer cards. They also tend to be touchy about AGP compatibility.

Pixel Shader 1.4 support was an interesting curiosity but apparently the chip had some oversights in internal caches so it doesn't perform particularly well with it. I think this came up with Doom3.

A FireGL 8800 is likely to have even more game quirks and likely to have reduced performance from its drivers being intended for professional modeling software.

Never used a Radeon 8500 or 9800, but have used Radeon 9600s quite extensively including playing games like AVP2, BF2142 and also older games like The Lost Vikings 2, Imperialism 2, Total Annihilation with it along with undoubtly many more games I can't remember atm.

If money is not much of an issue for you and you have some (unspecified) NVidia cards as backup, then why not just get it and try it and report back to us?:P

I would go for the 9800pro. Haven't had any problems with a shim, I believe that was a 9700pro issue. But with the 9800pro, you can run all Win98 games with AA+AF.

For a cheaper and cooler running alternative, try a Radeon 9600pro or xt. Still plenty fast, but less heat.

Shim problem existed all the way up to (and including) X800 series. They solved it by cooler design.