I recommend the Ecs 945GCT-M v3.0...I got it for $50..I support latest S775 45nm Wolfdale..It have onboard video GMA950, 4xSata, IDE, sound, NIC..2xDDR2 up to 4GB.
You can pair it with a cheap Celeron dual-core E1200 or even cheaper Celeron single core chip.
Cheap S775 board 
Linear Mode
