As one of its daily deals, Staples offers the refurbished Dell Optiplex 760 Intel Core Duo 2.8GHz Desktop PC, model no. ST1-0017, for $159.99 with free shipping. That's the lowest total price we could find by $20. Features include an Intel Core Duo 2.8GHz dual-core processor, 4GB RAM, 1TB hard drive, DVD burner, Gigabit Ethernet, USB, and Windows 7 Professional 64-bit. Deal ends February 28.
A 1-year warranty applies, although it's not clear who backs it.
Update: Specs corrected