It still wouldn't be an all in one regardless of specs. Everyone who's recently built a system knows how much one could build for $3,300, and yes it would be a monster gaming machine.
Bottom line is this: no all in one is ideal for gaming, and next to none of them are "good" for gaming relative to the premium cost one pays.
A 512MB 9600GT (I'm assuming non upgradable which is often the case with all in one designs) is at the bottom of current decent 3D gaming graphics performance. Essentially it's a sub $100 VGA card for a $3,300 system. Naturally, the emphasis for an all in one media PC is not 3D gaming.
I use a 1GB 9600GT myself with my general use media PC and it plays all recent games acceptably today (not at max settings for all games at 1680x1050), but I have a hard time seeing myself using the same video card in another 1-2 years at the very most.
If you spend $3,300 on a PC, I'm assuming it's one you're planning on keeping for a bit longer than 1-2 years, which will have minimal upgrade options as an all in one system.
That being said, the Vaio is unquestionably a premium system with solid specs all around and most likely has a gorgeous display to top it off. The built in panel itself would cost a premium if purchased separately.
I just wouldn't buy a premium all in one if one of the main uses was to be gaming unless the VGA card was upgradable and the PSU could support something like a GTX285 or even a GTX295 or HD4870x2 (highly unlikely).