This deal has ended.
Update: this is currently out-of-stock. Overstock has renewed their inventory and has a rare 15% off coupon valid through 9/21, resulting in the best deal yet on an Xbox 360. The Xbox 360 Platinum with hard drive is now only $339 after the 15% off coupon. Shipping is a wee $1.40 and there is no sales tax (except UT, IN). They also have the best prices on accessories.