MegaMacs offers the refurbished Apple Mac Pro Intel Xeon 4-Core 2.66GHz Desktop PC, model no. MA356LL/A, for $529.99 plus around $25 for shipping. That's $32 below our mention from three weeks ago (which featured double the RAM) and $169 under the lowest total price we could find for a similarly-configured used unit elsewhere. It features dual Intel Xeon 2.66GHz Woodcrest dual-core processors (four cores total), 2GB RAM, 250GB 7200 rpm hard drive, SuperDrive, NVIDIA GeForce 7300 GT 256MB graphics, and OS X 10.6 Snow Leopard. Deal ends March 20.

Note: A 30-day MegaMacs warranty applies.