Yeah 512 is enough for just your basic home computing, but for gaming, etc. your gonna want a gig, and make sure it's pc3200. Also, be sure to keep the 512 stick you have now and add another 512 stick cuz 1 gig single sticks have high latency.
I have a question about RAM and CPU's: 1. What is the main difference between Athlon 64 bit CPU's and Athlon 64 fx cpus? 2. What Sockets will Dual channal Ram work on? 3. How do I determine weather or not RAM is dual Channel?