Somebody let me know what specs I need to get on a laptop?

I'm looking at buying a laptop, but I know nothing about computers. Basically, all i need it for is music, porn, and general browsing. I've got a decent sized music collection to throw on there, and I want to be able to stream porn without it stopping to buffer while I'm buffering. I'm not planning on spending a lot of money, <$400. I realize that's not much, but there's usually good deals. Really just trying to get a guideline of some specs I definitely want to have.