there could be some games in 6-12 months that really benefit from a specific piece of DirectX® 11 hardware . . . personally I would be of the mind of crossing that bridge when I come to it! . . .
If that's the case then stick with XP. In terms of graphics, your not missing much atm.
DX 10 & 11 api's haven't been offering any major visual benefits over DX9, at least not in the way DX9 did over DX 8; that was a bigger change imo. Of course they'll always market new dx api's as the second coming...
A lot of it comes down to developers. Not many titles are being built from the ground up using the newer api's, because the majority of customers are running older platforms (DX9 machines, xbox360s, PS3). The software has to work well on those platforms. The new dx features are only being 'tacked on' in a few titles, and it's often hard to see the difference imo. A lot of it's just marketing. I think when we see a new gen of consoles, things will start to change.
Looking at your replies it sounds like you've made your mind up ages ago. I can't come up with a good enough argument to change it!
On a side note, I really like win7, quite a bit more than XP. It's a personal thing I guess....