Will a GeForce 9600 GSO 768MB work fine with a 500w Antec Basiq power supply?

It should. I was running a 9800GT on a 450W for over a year, and I was doing just fine. You're running a lesser card on a higher-capacity power supply. People will overplay the power supply thing. The 14-year olds who really have NO clue what they're talking about will tell you that you need a lot more than you really do. I used Newegg's wattage calculator to make sure. Their minimum RECOMMENDED wattage is slightly over 400 watts, and I did plug in all of your hard drives and everything. A 500 watt power supply is plenty.