Thanks phoenix
I spoke to ATI and they emphasis that the 6000 series is cheaper than the 5000 and is optimised for Tesselation. There was a bit of a language problem but I think he was saying the 5000s also deliver Tesselation (I've seen this in other posts) and he defintiely said the game has to be written for it.
I think Oleg has said it would be Dirext11 (hearsay from other threads) but I believe that won't deliver Tesselation on its own.
According to a couple of websites the 5870 is 'faster' than the 6870 except where Tesselation is used
http://www.hardware-infos.com/grafikkarten_charts.php
http://www.tomshardware.com/reviews/...50,2782-7.html
http://www.tomshardware.com/reviews/...arts,2776.html