Originally posted by: aelfwyne
I would have to say "Mostly" to that. I upgraded from a 9800 Pro to an x800 GTO (that I then flashed to 16 pixel pipes). There was a significant difference in framerates, and games such as Oblivion were much more playable than before. I would definitely consider it an upgrade. The x850 is yet again an upgrade... The mistake to avoid is the 6000 series nvidia cards. Your 9800 Pro is honestly close to a 6600GT in performance, and the x800/x850 series just obliterates anything below an nvidia 7800 series or better. Also, you would be better off with an x800/x850 than with an x1600/x1650 if you stick with ATI, since the x800/x850 were top of the line, while x1600/x1650 are mainstream products, despite being newer.
You can get a quick-n-dirty comparison here:
http://www23.tomshardware.com/graphics.html