My first laptop was a 10.5" HP 900. Fantastic machine, and fast (166 MHz). Back in those days this was the machine to have... Along with Compaq and some heave but competent IBMs.
Now it's another thing; HP and Compaq joined together and somewhere totally lost everything they knew about making good laptops. Now I have a Compaq (not payed for, got it thru my work) and it's crap, exactly as stated above. The *only* good thing is that the LED indicating it is turned on is cool - blueish...
and I nearly forgot, the 15" screen is good and the resolution is 1400x1050.
Today I would by either a Sony or an IBM. One with a good screen and a decent keyboard. But there are of course always different details that are important or not to different persons. The new broadscreen machines look tempting. I saw one at a major store here and found that the hefty 17" screen had lower resolution than my 15"...
Serial port? I can't recall when I last used it. The parallell port, ok for some writers and dongles. USB 2.0 a must, and if possible 4 ports.
Basically a laptop will never perform as well as a real good homebuilt machine. They seem to have slower busses, only one hard drive, lack in memory (or the memory is to expensive), bad graphics and so on. You will end up with some kind of compromise. One get surprised to see also "high performance" laptops getting sold with 256 meg RAm and /or poor graphic adaptors with shared memory, screens capable of 1024x768 max, and so on. Lots of details to check there...
Good luck!