Ok... are you looking for a reliable and portable laptop? or a Desktop replacement?
I dont suggest buying a Dell or Gateway or other things. If, like you said, you're willing to pay a reasonable price. Here are some good options:
http://www.voodoopc.com/default.aspx
Voodoo laptops and desktop replacements are awesome. Think Alienware, but not ugly. Think Mac, but very custumizable.
http://www.falcon-nw.com/
Falcon is amazing. They have the best customer service and support if you have time to read it. And they use the same automobile paint for their laptop's paint jobs.
Unlike the systems you'll get when you buy premade ones, Voodoo and Falcon lets you customize it to your heart's desire. From how much memory to what kind of video card you want in it, from what color to what tatoo or picture you want on it. You can actually play around they're websites and see how much having them assemble one for you will cost. The price isn't so bad... it's very worth it actually.
But if you just wanna buy something that's already premade... i suggest you buy a MacBook, a PowerBook, or an iBook G4 from Apple. Apple laptops are great.. we all know this.. they're very cool looking too. Don't buy MacBook Pros right now though... i heard they're having problems.
As for specs, choose processors that are MADE for laptops, like Centrino Duo. or AMD Mobile Athlon 64. IF not, they'll get too hot and crap out.
For RAM, get 512 MB MINIMUM. Don't get anything lower. If you wanna play Games on it, I suggest 1 to 2 GB.
HardDrive capacity is up to you really... but 60+ GB is advisable.
Videocards also depend on what you wanna do with the laptop. Videocards can be expensive, but you have to decide before you buy the laptop if you want an upgrade, cause its not as easy to upgrade a laptop's video card as it is with Desktops.
Wow.
Well.. I hope that helped. lol
P.S. AND OH! The good thing about voodoo, falcon and apple, is that when you get them, they're hard drvies are completely clean. Unlike premade laptops tht has alot of crap on it like useless McAfee or AOL Trial. And you get an actual (for voodoo and falcon) Windows CD, cause having windows preinstalled in a partition of your hard drive sucks.. believe me it takes up valuable space.