Lets see.
8 in the media room.
8 in the server room.
3 in the kids rooms.
1 in the work shed.
No need to turn on the heater in winter.
Yeah, my basement office is a bit warmer this winter than last -- that's what happens when you up the machine count dramatically
On a side note, I'm seriously considering going Solid State in all my machines in 2008, and having the big storage protected in a Raid Z setup.
Cheers,