I used to build budget systems for myself.
Last time around, my friends got the ASUS P4C800-E motherboard for something approaching $200, and I got a P4P800 (Standard). It was a good choice -- now replaced with a P4P800-SE that I picked up for $95 in retail shrink-wrap.
Now, I'm looking at "top-end." I've been following the ASUS boards that include the P5WD2-E, P5B, P5W DH. The P5WD2 has been a disappointment for many people looking to upgrade to Conroe. I had my eye on a workstation motherboard -- the P5WDG2-WS, but it didn't seem "Conroe-ready," and some Newegg customer reviews show varied results. I x-ed my fingers with a thought that this workstation board would come out in revision. It did -- see my query posted a couple hours ago.
But that's over $300. I'd say -- only from what I've heard, and for your needs, the P5W DH should do it. It got a "kick-ass 9" award from Maximum PC -- if you believe everything you read in that mag, but there's probably good reason why they rated it highly.