take the catalog and compare both model features and price range and make sure that if any of your friends got those models and collect the feedback with them. Now you decide that which laptop is better for you!
Dell laptops do crash more often than HP laptops. HP laptops also seem to last longer. The specs on HP laptops tend to be better as well.
Try i5 with Dell or HP, but make sure to compare the features and configurations of both model (ask the showroom person to give the features and configuration brochures).
I've had both. An HP laptop and I currently using a Dell desktop computer. I was pleased with both, so tough to say. I really don't think you can go wrong either way. If you're looking for monitors though, I'd definitely go for Dell.