Netbooks don't have the horses, and they certainly don't have the heat dissipation capability! Sounds like what you have can get you started....although you'll find real quick that really old hardware is in some cases too slow. Well....

 

This is the 3rd iteration of the rendergarden. Except that the netgear 24 port 10/100 switch has been replaced by a green gigabit 16 port smart switch. The original boxes above ran an original Slot A Athlon, and the rest were Athlon IIs. The current boxes in the rack run Athlon 64-'X2s. All have 4 gigs ram. A couple of them also have a RAID 0 HDD array (experimenting. It does speed up the slowest part, namely hard drive access time, but you have =zero= error tolerance. Lose a drive, and you have to reinstall everything). When the new chip cycle starts, I plan on upping the current rack boxes to AM3+ motherboards (meaning they could run the upcoming Bulldozer octal core processors), but getting the best deal on the strongest quad core chips I find. I built the rack so that I could just swap out the guts and not have to worry about a lot of cables and case issues. The rack kits can be had at a reasonable cost; the cases are a bit costly, but they will mount -anything-....and as the vast majority of them are steel, you don't have to worry about them getting dented by anything short of a sledgehammer.

 

Plus is you get a slightly clued person asking, you get to watch their eyes bulge when you tell them its your renderfarm...... :P