cfvh600 :
Check Dell's website for CPU support.If you can't find anything then contact their customer support.
Hahahahaha, call customer support. That's a good one. I did the same thing last night because I'm going to upgrade my E6600 to a Q6600. They told me I couldn't update my processor or at least they stated they couldn't tell me if the mother board would support any other proc.
They used to do this in the past. That about put the nail in the coffin for me not buying dell anymore unless it's a cheap throw away I need for something.
To answer the original question, go to their support. they do have a decent way to pull up the user manuals for most of their machines. It'll probably just say it supports Core 2 duo's. But you should be able to get the board chipset and figure it out.
Personally guess I'm trying the quad and if doens't work ordering system board and trying to torch it into the dell case and if that doesn't work get a case.