there's really nothing wrong with any brand. Depending on who you ask they'll tell you something different. A sweatshop can make a suit that's worth $20, but once it has a 5 cent Armani tag on it it's worth 2 grand now. Name brands shouldn't be something to get too worked over. Both HP and dell are great for customizing whatever specs you want. Sony has a bit better customer service and a ton of programs per-installed made specifically for that computer. Lenovos seem to be good specs for what you pay. Who I work for has literally hundreds of lenovos; I don't have a problem with them. I have never owned a Toshiba but many of my friends and co workers do and I haven't heard them complain.
If it's a name you have heard before and isn't vizio or coby, it shouldn't be anything to get too worried about.
Personally, I like SONY, but the prices are a little high for what you get.
I'm using an ASUS laptop right now and love it. My boss also happens to have an ASUS laptop, but his was way more expensive than mine. But he talks about it all the time and brings it in for presentations every chance he gets. And because they Make The Motherboard: there's one more reason to buy.
A lot of people will talk poorly on Dell computers, but those same people talk about how awesome Alien Ware is.. I don't know man. I don't know.