BuyDig.com offers the HP Pavilion MS225 Athlon II 1.6GHz All-in-One 19" Desktop PC
, model no. AY587AA#ABA, for $568.95
with free shipping
. Outside of the price below, that's the lowest we could find by $18. It features an AMD Athlon II 250u 1.6GHz dual-core processor, 18.5" 1366x768 widescreen LCD, 4GB RAM, 320GB 7200 rpm hard drive, DVD burner, 802.11g wireless, 1.3-megapixel webcam, and Windows 7 Home Premium 64-bit.
Of note, B&H Photo-Video has it for $569.59 with free shipping.