The p2 350 wasnt the greatest of overclockers, but it was made from the same wafers as the 450 I think, so speeds close to 500 might be attainable with a little cooling, 400 - 450 without.

Remember, you cant change the mulitplier on these chips, so you'll have to modify your bus speed to get the speeds you want.

As long as you have a few choices between 100 and 133 (bus)just move on up a few mhz at a time and run some tests until it starts crashing, 400 should be well within reach.

As far as video cards go, its the ram that makes the most difference, so get that as high as you can. for Nvidia(GF2, TNT2 etc) I'd use NVmax or Powerstrip. Good luck.