Well, the answer that you will get from the vast majority of tg forum users is that you should get neither.
These are my quick picks for gpus:
<100 : Sapphire X1650 $55
100: evga 7600gt
<150 : evga or xfx 7900gs
<200 : X1950Pro or X1950XT
250 : 320mb 8800gts
350 : 640mb 8800gts
The 7950gt costs more than the X1950XT or Pro and has significantly lower performance. The 7900gs has very similar performance for much less money. The 320mb 8800gts costs slightly more but has MUCH more performance.
There is no reason to get the 7950gt unless you need Nvidia and HDCP but dont have enough power or cash to get a 8800.