Well,
I heard that MOST 750e's don't overclock beyond 110-115 FSB which only gives you 10-15% OC, unless you use special cooling
Good luck
Let me knwo how far you get with it, because I am thinking of moving up from my 600E (whihc OC's beautifully to 900). If you did not get any cpu's yet, just get the 650. With the right mobo, like the CUSL2 which lets you adjust the FSB:SDRAM clock ration to 3/4, youc an achieve crazy speeds.
Good luck