I've been looking at benchmarks and the 9400M is only a little better than the 2400 and comparable to the Radeon 2600 at decent resolutions.
The 7600GT was a pretty decent gaming card a few years ago and will still play many games with good frame rates but as caveman said it lacks the latest features for snow leopard and HD content.
I'm not impressed with the new range at all unless you have the money to skip the 9400M and get the GT120/130 even then your paying alot and its not a 260.