Compaq Presario 15.6" LCD, Dual-Core 2.0GHz CPU, 2GB RAM, 250GB HD for $399.98 shipped after this $30 rebate.  It comes with AMD dual-core QL-62 CPU at 2.0GHz, 2GB RAM, Geforce 8200M graphic chip, 250GB hard drive,  wireless 802.11b/g, integrated media reader, DVD burner, and more.  Another version of this laptop but with a smaller 160GB hard drive is available for $379.99 after a $30 rebate and a $70 rebate.  Note that this is a budget laptop and at 6.52 lbs, it is more like a very portable desktop instead of a  truly lightweight laptop.  For the other end of the spectrum in terms of extreme lightweight and portability, check this out.

Originally posted earlier, this deal has been revised to include the 160GB version of the laptop.