I'm not even going to bother opting for a Direct X 10 card yet. From the reviews I've read, the patches at least for Direct X 9 games, to make them 10, even send the 8800GTX spiralling to its death, even at low resoloutions according to Custom PC.
So I'm definietly going to wait to shell on a card that expensive, until we have proof, because running Direct x 10 well won't be enough in a few years, and I want my parts to last.
My card at the moment is an 6800GS (overclocked by BFG), but it has temperature issues, and causes a few artifacts.
At the moment, the temp is 76 degrees C... and thats idle!
With a 46 degrees C ambient temp (so its not like the case is hot)