You don't need 8GB+ RAM for gaming. I only have 16GB for 3D work(although I do run out sometimes, so I keep debating a full dual hexcore workstation, if only headphones didn't suck up so much money).
I wouldn't even bother with a hard drive in a new build now with 480GB SSDs going for £200. I'm planning to go all SSD in my main rig in the new year. That and a new pump, current one is starting to die.
EDIT: Well, maybe a hard drive for hardcore archiving or a server.