What are you just a casual gamer or just plain stupid and want the best graphics and performance? Then get the 9800 since it's equal to a 9700 Pro and is still pretty good (rare though).
If you are a true techie and you know you won't fail if you flash it to a 5950 Ultra, get the 5900.
BTW. i voted for the 9800 not knowing it was actually a regular 9800 instead of a 9800 Pro.... BAH.