Ok, well this is just a rough estimate, but since it's based around a Geforce2, I can make a guess. I'd say about 300Mhz Core, somewhere there, and maybe 500Mhz or so memory, maybe a little further. Just keep increasing slowly by a few Mhz, test it, then run it. Back it down if you get instabilities.
I need my Hammer now to bash some newbies