Well its hard to get around 95W extra for the video card only on a 300W supply, especially if you have a quad-core CPU etc.

But reviews suggest that a system with 2.2GHz Core 2 Duo ,2 GB ram, single HDD etc. and the 9600gt draws about 190-200W total under full load. So, if a PSU can handle that coolly, I think it shud be stuck with. But of course, to be on the safer side, get as good a PSU as you can.