Looking to add some RAM plz help!

Right now im running 2x 512 sticks of Corsair 3200 XMS RAM, looking to buy another 512 stick for around 100-150 dollars or so, what is the best option here? get exactly what i have now? get alittle faster? whats the best bet to keep my computer running as good as it is now?

http://www.newegg.com/Product/Product.asp?Item=N82E16820145520

ive found that stuff but its ultra performance not XMS though the timings are still 2-2-2-5??

Adding another 2x512MB of better RAM to run with your current sticks won't help because it will automatically default at the slower clocks. The best thing to do is to get 1GBx2 so that way you will avoid this problem and also be able to run at 1T command rate.

thats exactly right u will have to run to the highest timings. secondly i suspect ur not gonna be able to oc as well cause ur running an odd number of stix...