Out of the two, I tend to prefer Dell, since I've dealt with Customer Service and Tech Support from both products, and Dell tends to be easier to work with. I've never been disappointed with a Dell lappy, other than the fact they're all Intel based. I'm not sure if HP is using AMD as of late, but still not my favorite brand (HP). Toshiba makes a decent Satellite notebook from my experiences, as well as Lenovo.
(I assume you're not the most computer savvy since you're asking between the two, but if you are, build your own PC, and you'll be much happier!)