I have a Dell E1705. My wife has a HP (I forget the model number). We both like our notebooks.
If I were to do it over again, I'd probably get a HP 17" notebook. My dad got one and it came with a TV tuner card and a numpad built into the notebook keyboard.
If you go with a PC instead of a Mac, I strongly encourage you to back up program install files, wipe the OS, and reload the OS and only the programs you need. Almost all new notebooks come infested with trialware, ads, and junk you don't need and won't use. I wiped and reloaded my wife's notebook; it took several hours, but I think it was well worth it.
EDIT: Also, I'd recommend staying away from Alienware. When you buy Alienware, a significant percentage of your portion is paying for the brand name. I'd recommend custom-configuring a Dell or HP laptop to match (or nearly match) the specs of the Alienware notebook you're considering. I think you'll find it shaves a few hundred dollars off the price.
EDIT: Oh, and make sure to look for coupon codes and specials from whatever vendor you decide to buy from. If you're not in a hurry to buy a notebook, you might want to watch the sales and wait a few weeks until you find one that's particularly good.