Techgage posted a review of one of Intel's mid-range Xeon Quad-Core - the X3210. Here's an excerpt:

How the X3210 compares to others out there is a tough one. Dollar for dollar, I would easily pick up the Q6600 for the fact it has a faster clock speed and a 9x multiplier, while the X3210 has only 6x - 8x multipliers. This normally won't mean that much anyway, since most motherboards will hit 400FSB with ease, which would give you 3.2GHz. As we found out in our case though, that clock speed will not likely be possible for most people, without heat getting in the way.

If you are simply looking for a Quad-Core at the best price, you cannot go wrong with this one. It retails for $260 - $270 and offers four cores at a very respectable clock speed. It's rare to see a value like this... and just last year, it would have not crossed our minds. That said, if you -are- interested in overclocking a Quad-Core, do what you can to find a G0 revision, as they have slightly lower TDPs and tend to overclock better.

With Penryn right around the corner, the decision to pick up a processor now is made more difficult. However, Penryn is not going to launch at rock bottom prices like the Core 2 Quads are now, because they are revamped architectures, not simply clock bumps. With prices this low, you are not going to go wrong, with whatever you choose.