Ok, so I have a new miner rig on order.  AMD CPU, 3x6990s, 4 Gig RAM, 30 Gig HDD.  I too the recommended list of parts from the wiki.

What OS should I use?  I would rather use Linux (which flavor) but will run Win7 if that is what gives the best performance.

My plan is to run it headless stuffed in a corner of my office and just let it crank away 24/7.

My cost was about $400 less than NewEgg buying direct through my distributor.  The 6990s are on back order but they should ship next week, just in time for the difficulty increase :/