what's performance difference can you see with different latencies? I currently have a setup of:(2) 256mb pc3200 at CAS 3.0(2) corsair valueselect 512mb pc3200 at CAS 2.5recently i've hear of 2-2-2-5 or something like thatand overclocking memory? how is that all done?

To put it simply, latency refers to how long the motherboard waits between each communication with the RAM. Thus, the lower the latency the faster the RAM.I don't know the specifics around each individual number but you're right, as far as I know, 2-2-2-5 is the fastest available right now.You can change the latencies in the BIOS settings. Your use of mixed CAS numbers will mean that your motherboard can only run stably with the slowest (i.e. highest) CAS setting (in your case, 3). You can obviously try to force it to 2.5 in the BIOS but that would mean running your 256MB sticks at a lower-than-specified CAS setting and could risk stability.The performance impact should not be much in any case but should be more noticeable in AMD Athlon64 platforms than on Intel platforms. This is to do with AMD's use of an integrated memory controller in its CPU.Hope this helps.Edwin