I went with the Optiplex 990 tower. i7. 3.4 ghz, 4 GB ram (will bump to 8 or more) 500 GB hdd, Ati 1 GB video card, Win7-64. etc.
I had to get some cables to adapt the SATA power to LP4 to power the card. And, added a 1 TB hdd for the video files. I'll likely add an external eSata enclosure for some more space.
It's all working fine. CPU utilization rarely gets above 5 - 6 %. Quite amazing. I'm now thinking about getting another one to upgrade my server to SBS2011.
thanks guys!
Chris