TigerDirect offers the 5.5-lb. HP ProBook 4540s Intel Ivy Bridge Core i3 2.4GHz 15.6" LED-Backlit Laptop
, model no. C6Z36UT#ABA, for $499.99
for shipping. That's the lowest total price we could find by $28 and the first laptop we've seen with Windows 8 Professional without additional upgrade requirements. Features include an Intel Core i3-3110M 2.4GHz Ivy Bridge dual-core processor, 15.6" 1366x768 LED-backlit LCD, 4GB RAM, 500GB hard drive, DVD burner, 802.11n wireless, Gigabit Ethernet, 6-cell battery, and Windows 8 Professional.
Note that this system comes with Windows 7 Professional pre-installed and includes a disc for installing Windows 8 Professional.