I recently built a system for a co-worker that plays live-EQ and 3 boxes. All parts were bought off
www.newegg.com and came out to $635 after shipping.
Asus P5Q Intel P45 chipset mobo
Intel Core2 Duo E7200 (45nm wolfdale) 2.53 GHz
2x 2GB OCZ Platinium DDR2-1066 Ram
Nvidia 8800GT 512MB made by EVGA
Western Digital 750GB HDD
generic SOHO case w/ 600W PS and 4 fans