BuyCoolGadgets via Newegg offers the refurbished HP Compaq DC 7900 Intel Core 2 Duo 3GHz Desktop PC (no monitor), for $99.99 with free shipping. That's $60 under the lowest total price we coudl find for a similar refurbished model elsewhere. It features an Intel Core 2 Duo E8400 3GHz dual core processor, 2GB RAM, 80GB hard drive, DVD-ROM drive, and Windows Vista Business. Deal ends September 24.
A 90-day warranty applies, however it's unclear who supports it.