Forget all this DX10 hype and get real. 95% of all games are DX9, and
upcoming games will support DX9 no doubt, because DX10 is not even
1% of the market.
The market is predominantly DX8 and DX9, with some DX7.1 thrown in.
So you can safely get a DX9 card which will kick the a$$es of both of
these cards mentioned.
What are your options?
Well, you can easily go for a 7950GT, or push a little higher
and go for a 7950GX2 (single slot SLi card).
Either of these cards are wicked sick performers and give superb framerates
even under ridiculously high settings. (Check
www.guru3d.com if you don't
believe me).
The XFX 7950GT XXX edition is the best thing to have, and not just cost
wise (which is very very reasonable), but because it just rips through all
games you can throw at it.
Now if someone wants to run F.E.A.R at 2560x2048 with 16x Anisotropic
Filtering and 8x Anti aliasing with full lighting and all effects turned to
max, that's a different issue. BTW, even then, this beast will do about 20
to 25 fps, if your ram and processor are good. Those cards which you are
considering right now will have their panties up in a bunch and catch fire
under the settings I mentioned.
I've seen too too many of my friends go for these garbage cards, and it's
disheartening to see them upset due to low framerates in every game.
E.g., My 7900GS XXX edition (Overclocked) coupled with my P4 3.73
Extreme Edition just KILLS any game I throw at it, at resolutions like
1280x1024. True, higher resolutions suffer, but hey, it doesn't make me
a difference because 1280x1024 is a fabulous resolution, and my monitor
doesn't support anything higher!
The other day I compared the performance of the card against and
8600GT with the same game under same settings, and boy, was I happy!

(And sad due to an upset friend).
So watch it, be wise, stay away from the hype, and make a wise decision.
After all, the thing that counts is the framerates you get, not DX10
support.
Anything less than a 8800GTS 320MB for DX10, or an HD2900XT, is
crappy. Take it from a person who has sat his posterior testing almost
all cards recently and not so recently released by nVidia.
Happy gaming!