I run EQ2 on an AlienWare Area 51 with 2 gig RAM and it's smooth as a box of frogs. Can't recommend their gear enough - you get what you pay for, and it's nearly as upgradeable as a desktop (it replaced my esktop completely). Mind you, I wouldn't call it 'lightweight'!
BTW, on a wireless network I can play lag-free, in windowed mode, with Alla or GamerGod in the background - it's truly excellent :)