Hi.
I want to do some virtualization using either Sun’s Virtualbox or Vmware. I will use Ubuntu as host operating system and I want to run about 8 installs of XP concurrently as guests. All of these XP guests will simultaneously do stuff on the web.

I need to buy a monster machine to handle this. My money can either buy me an i7 cpu with a little DDR3 ram (4-8gb) or a Quad Core (q9400) with about 16 gb of DDR2 ram.

It seems like the cpu is powerful enough in both cases, but I believe the extra 8gb or ram will come in real handy when it comes to virtualization. I believe the bottlenecks in virtualization would be located elsewhere, such as I/O. Please tell me what you feel would be my best choice.
4 answers in about 10 minutes… wow ! Are you guys on standby waiting for these questions ? Anyways, thanks for the good answers so far. I will wait a while until I award the winner to see if some more geeks respond. Please keep ‘em coming people.
I respect the opinion that the i7 is the fastest cpu and is good with virtualization, but I think i will go with quad core, cause I believe I need as much extra ram as my budget will buy. Honorary prices to all that suggested that Quad Core is the way to go, Quad Core is what I will choose. I will vote for user "Divot" as the winner though, because of his valued opinions about cache and DDR3. Thank you all that responded.