Staples has the HP Pavilion a4316f-b Desktop + HP 2009m 20" Monitor: AMD Athlon II 2.6GHz, 6GB RAM, 1TB Hard Drive, Windows 7 Premium for $674.98 - $50.00 rebate [Exp. 06/26] = $624.98 + free shipping.
NewEgg.com has the HP Pavilion Slimline s5360f Desktop PC: AMD Phenom II 2.8GHz, 6GB Memory, 750GB HDD, Windows 7 Premium for $819.99 - auto $50 off in cart = $769.99 + $19.99 shipping.
Best Buy has the Gateway DX4822-01 Desktop + 20" Monitor: Dual Core 2.6GHz, 6GB RAM, 1TB Hard Drive, Windows 7 Premium for $599.98. Shipping is $39.7, or choose in-store pickup to save on shipping.