you dont NEED AA or AF of any kind enabled. the 9600XT is only 1 generation behind. The great thing about it is its CHEAP. It will still run most things at 1024 x 768, so whats the problem? The next best card to get would be a 6600 GT, which is the best value latest gen mid range card.
Overclocking is easy for ATI cards. Install the latest catylist drivers, bring up your video properties, click the "vpu recover" tab, and check that is enabled, then move to the "overdrive" tab, and enable that. Thats the easy way, with limited results. Its safe, and under warrenty.
If you want to kick it up a few more notches, download this:
http://www.techpowerup.com/atitool/Install it, click find max core, let it do its stuff.. then find max mem. Once its done that, back off the speeds of both by about 2mhz, 5 to be absolutely safe. Then test it properly with a bit of gaming and benchmarking. Look closely for artifacts or tearing.
I recomend 3dmark 2003 for benchmarking this card, the benchmark is the same age as the card so it will give a better idea of performance gains. You can get it from
www.futuremark.com