Great thread Dave, as always. Welcome to the team NoL, cabbspapp & bootup05

Just a sidenote for those who have more to spend, but care very much about efficiency: The most efficient rig for WCG you can currently build is a dual Harpertown (Octacore) rig.
Initial cost is high, but with outputs ranging from 30000 to 40000 points a day at below 300W power drain, this is a force to be reckoned with. It's also about the fastest thing you can get if you're doing CPU-intensive simulations of any kind, raytracing or video editing.

Parts needed:

- 2x E5420 S771 Quadcore Xeons, approx. 600 USD
- Asus Z7S WS mobo (there are cheaper mobos, but this one's overclockable, standard ATX size and also draws very little power) - 500 USD
- at least 2x1GB DDR2-800 FBDimm memory, appox. 110 USD
- good quality EPS capable PSU (24pin + 8pin + 4pin connectors), should have high efficiency (for example Corsair HX520) - approx. 110 USD
- Case should be well ventilated, other than that you can use pretty much any case as long as you're using Intel stock coolers
- generic hdd and any GFX card, even PCI and you're set

So if you have appox. 1500 USD to spend this is the way to go.