P4PE Ram question & WD Raptor coming in

Hey I bought a P4PE board about this time last year from www.pcnut.com w/ 512 of Mushkin 2700 & a P4 2.4B & was very pleased. Well now it's tax time again, & I was debating if to just get another stick of 512 2700 or could anybody recomend buying 2 sticks of faster 512? What is the fastest ram that I could get for this thing anyway? Asus's site isn't the greatest for these kind of questions. Would there be any REAL performance increase going to say 3200? Also I am buying the WD raptor 74GB edition in a few weeks & might get the ram @ the same time.
thanks to all

memory

corsair 2700 cmx512 xms series gaming mem

As for me I am boycotting Corsair. I am not happy with my 3200. The best RAM that I have seen being sold is pc4400/ddr550 . Obviously thats the best RAM you could get. Ive heard that there is ddr600 out but havent seen it being sold anywhere. Like I said in another post BAD RAM=BAD O/C . So dont do what I did and get low rated ram that will hold your o/c back.