Cluster hardware... PS3, Core2Quad, Xeon, questions

So I started a thread in Alt OS about cluster computing software but I really think the hardware portion of my cluster-quandary belongs here, in General Hardware. (But I'm willing to have this thread moved if there's a more appropriate place )

A good friend and coworker has been talking with me a lot about building a cluster or two as part of a small business (ad)venture and we are trying to figure out what would be best for hardware.

We understand that the Cell processor in the PS3 is really powerful and the price tag on the PS3 is great for cluster-minded buyers *but* I am wondering if Xeons or even Core2Quads would perform just as well?
My guess is that the PS3s will perform better... we'd like to set up a smaller (or just less powerful; not necessarily smaller in physical size or number of nodes, heh) cluster as well and it may be Core2Quads or Xeons.

Advice?

P.S. If you have comments and advice on cluster software and OSes then please reply to my other thread here (Alt OS forum) to keep this thread on topic.

C2Q chips to me would make much more sense from a programming standpoint. Unless going with a very large high end cluster I think it would be hard to justify the custom programming for the cell processor.

A great resorce for the set-up would be the Team 32 and SETI guys. Some of them have some very nice folding farms and could give you a have with set-up ideas.

Yeah, the downside to the Cell processor is architecture. =/ There's not much in the way of software for it that doesn't just run in the PS3 OS/firmware/whatever they call it.