I don't know much about laptops really. But I do own a Dell Inspiron something. It has a good graphics card. It came with a bluetooth (wireless) mouse which is useless for gaming - I think you'll want a USB mouse with cord for that. Unless you think you can play using that horrible track-pad thing with your thumbs.
Laptops, being compact, have more expensive parts and tend to overheat. Probably not the best choice unless you really want the portability. 320GB hard drives are pretty cheap now, I have two of those on my desktop machine. It has vista, so I have all the music on the desktop, and my (also vista) laptop detects the media library and I can play music on the laptop.
As you may know, every new game release uses some new technology: "requires Direct-X 12.0 with pixel-shader 3.4 support" or some nonsense like that, so make sure you get a good gaming card. On the Dell, that added a lot of $$ to the price.
Or get a mac!