Does the $600 include a warranty? Because if it does, you're going to have to go with a bargain basement solution. I recently purchased a very cheap HP
that runs FFXI without issues, but might not be able to handle upgraded WoW. My total cost from Office Depot was $605, including a 4 year warranty and one free battery replacement.
If $600 is the base price and you have another couple of hundred dollars for the warranty, PC Magazine recommends this Acer Aspire over here.
It has a much beefier set of specs, and has actually dropped $100 in price since they wrote that article.
get a warranty on your laptop. Three years at minimum, four years if you can swing it. I consider warranties on desktops to be optional, but on a laptop, it's not. If you choose to skimp on the warranty, I guarantee your power supply will snap off 2 months after the 1 year manufacturer's warranty ends.