Nvidia GeForce 8600 series will launch in the middle of 2Q
 

Right after AMD R600..

"Nvidia is preparing to launch a series of GeForce 8600 cards in the middled of the second quarter 2007 to help satisfy the increasing demand for DirectX 10 supporting graphics cards caused by Windows Vista, according to market sources. The GeForce 8600 series will be priced to target mainstream markets, the sources add.

http://www.digitimes.com/news/a20070216PD209.html