Are you all stuck in Nvidia fanboy mode?
The RV670 (HD3000) core is an R600 run at 825+ MHz plus AA fixes. This means its performance will be significantly higher than the HD2900XT (the HD2900XT is about equal to the 8800GTS) and so this new line will be at least as powerful as the 8800GTX while being around $250 and on the new 55nm process making it very power efficient. This information is widespread and consistent. There is likely to be a clocked-down version equal to the HD2900XT/8800GTS at $200 too. The R680 core will be the high-end variant of the RV670 and will be released in Q1 2008. That should be easily more powerful than an 8800Ultra and cost less than a current GTX.
Then, in the middle of next year, the R700 (entirely new architecture) should arrive, bringing even more performance.
All of these will support QUAD CROSSFIRE.
Nvidia has no plans to support DirectX 10.1, but ATI will introduce it in the RV670 series.
The open-source drivers are progressing well, and ATI will add AIGLX support to their fglrx driver this month which will support Compiz Fusion, adding to the across-the-board 100%+ performance improvement last month.
Ubuntu. Linux for human beings.
If you are interested in trying Ubuntu or Linux in general, PM me and I will answer your questions and help you install it if you wish.