Yep, you can tell from the Steam hardware surveys just how popular that combo is. At the moment, 21% of users have an 8800/9800 and a further 12% have a card in the Radeon 4800 range, which is roughly comparable in terms of performance. In addition 57% now have a dual core processor, and 24% have a quad core. The number with a quad core is increasing pretty rapidly, as can be seen here.
What amazed me was that over 75 million graphics cards were sold last year. Obviously not every one is going to be top of the line, but equally, it will be consumers buying these, not businesses. ATI shipping a couple of million DX11 cards in just a few months was a real eye-opener, especially as they couldn't make them fast enough to keep up with demand. The base is certainly there now, I just hope we get more games targeted specifically at the PC, and rather less of the shoddy ports we've been blighted with over the last few years.