There used to be a real build quality difference between the Latitude and Inspiron lines but now some of the Latitudes are just black-painted Inspirons with marginally better support.
I'm not talking about Inspiron vs. Lattitude, I'm talking about the home line of Inspirons versus the SB line (9300 vs. 9400, when I bought mine). I find Lenovo's displays intolerably bad.
I don't recall exactly, but there were at least two components -- the video card and wireless card IIRC -- that worked well with Linux on the 9400 but not the 9300.
....And IBM Intellistations for desktop use. They're almost studio pc quiet, built like a powermac, and I have never had a single problem with one. They even ship with a decent keyboard. Just can't go wrong buying IBM....