Dell D820 only supports 3326 MB of memory.

Contrary to the website and the claims when I purchased this laptop, it DOES NOT support 4 GB of memory. Apparently because they are using an old cheap chipset that only supports 3GB, they make this ridiculous claim that they need 500MB for PCI express, and 250MB for shared video. You can read more about this on the Dell Forums.

As happy as I have been with this laptop, I am going to think again about a DELL, not that there's much choice out there.