I don't suggest the Prescott (3.0E) chip if you plan on overclocking or pushing it.
I have had alot of success with the Northwood (3.0C), pushing it to 4.0ghz. You can go 3.6ghz straight from the box.
As far as mobo's... I run the Abit IC7-Max3. This is one nice board. I have been a die hard Asus user, but the Abit outperforms the Asus (P4P800E Deluxe)... I was deciding between the two. My friends had the Asus and got rid of them in favor of the IC7.
Andy has it down pact about the ATI 9800Pro...