HP PC Desktop, Core 2 Quad 2.5GHz CPU / 6GB / 640GB for $474.99 shipped.  This system features an Intel Core 2 Quad Q8300 2.5GHz quad-core CPU, 6GB RAM, 640GB drive, Gigabit Ethernet, LightScribe DVD burner, memory card reader, and Windows 7 Home Premium 64-bit.  Here are the steps.

1. Click here to start configuring the system and select Base Configuration
2. Select Free Upgrade to 640GB Drive and click on Review & Buy
3. Add it to the cart and apply code SVNY56474 as shown in this screenshot.