I have experience with Mac, Dell, Toshiba. The Mac is my girlfriends and I am not so much a fan but from what she says if you want to do video work it is the way to go. Plus it is more resistant to spyware and viruses because when any software is to be installed it always brings up a dialog for administrator user name and password.
Ok, the toshiba and the Dell. Out of the two, the Dell is my favorite. I just sold it however on ebay because of the toshiba. The toshiba is supplied to me by work so the Dell didn't get much use, so I sold it because it was just sitting and depreciating in value. The Dell was fast and I am happy with their service. My harddrive went bad and they sent me a new one and picked up my old one from my apartment. I only paid for shipping. But here is the kicker: The new one they sent me was an IBM 40GB and my old one was some kind of 30GB, the IBM HD kicked total ass. Plus they loaded all my software for me, once I got it all I had to do was slide the old one out and slide in the new one, it took less than 5 minutes.
My toshiba has some minor issues (it is one of the satellites mentioned above) but they are both under factory recall and they are not major enough to break my productivity to send back in (plus I couldn't get on CR). It is pretty fast though, fairly light and comfortable to type on. So its not a bad choice
All 3 of the laptops I have are pretty much desktop replacements. After using the Dell and the Toshiba I would probably not go back to a desktop, although there is a Sony Vaio sitting behind me that is the fastest computer I have ever used. I had a very good experience with Dell, I would recommend them if you can find a laptop to suit your needs. As for my Toshiba, its not bad. It is a couple years old so I would think that they have their issues worked out by now. All four of us here in my office have toshibas and nobody has complained. I am slated to get a new one in a couple months though so my hand-me-down toshiba will see its 3rd owner. I hope this turned out to be a little more useful than some incessant babling.