It seems "How Low Can You Go?" is the question answered by the guys over at ExtremeTech. They have released a small guide to build a low or ultra - low budget PC. It starts off by saying: "This time, we're really stooping low - and it's all to save you money. We build four budget systems, as low as $630 with monitor & XP, ponder tradeoffs, and test performance." For the full read warp 2 ExtremeTech.com.