CORSAIR XMS2 DDR2 800 (PC2 6400) - Max overclock?

I recently bought this: http://www.newegg.com/Product/Product.asp?Item=N82E16820145590 but still haven't had a chance to install it into my system.

What kind of overclock can I expect to take it to? What speed and how tight timings? I know this kind of thing usually varies depending on what motherboard you have, but if someone could give me a general idea of what to expect, it would be helpful.

Thanks!

We have seen some in the lab over DDR1000 at 5,5,5 timings. However, most of them average much closer to DDR900 at those timings, using 2.1v.

How much better do the cas 4 versions fare?

My mistake, I quoted the CAS4 version. I have not seen any results posted with the CAS5 version. For the money, I'd get the CAS4 version.