The question the OP probably wanted to ask was:
5900 Ultra or 9800 Pro?
Which a lot of people have answered. But for <$200 the question should be:
5700 Ultra or 9600 Pro (maybe XT?).
I'm a long time Nvida user but I would go with the ATI cards simply because performance is basically a wash but the ATI's have come down in price a lot more.
Newegg has the 9800 Pros for $229. 9700 Pros are $190, so I'm sure the 9600 Pro/XTs are in that range too.