FWIW I have had considerably more HP machines with bad motherboards (both desktop and laptop) than any other manufacturer. Their consumer line seems to have some pretty horrible engineering as well, such as having to completely disassemble a laptop to do an lcd swap, or their desktops using flathead/hex screws while virtually everyone else uses phillips.
I think I've had the fewest problems with Acer laptops. I've been recommending Dell to people lately, but some of their newer laptop models have some retarded engineering, such as having to remove the motherboard to replace a hard drive.
Toshiba's are decent though they could get by with about half as many screws as they have. They also seem to have a tendency to run warmer than other laptops. Asus laptops are a royal pain to work on and get parts for, especially the souped up gaming laptops. Gateway and eMachines are basically Acer now, though they seem to be lower quality than Acer brand laptops.
Compaq is basically HP now, but I've had fewer problems with Compaq branded machines than I have HP branded machines.
I track all computers by manufacturer, if I ever get around to it I'll write a script that reports how many computers we get from each to help compare numbers. The way things are going though, I probably won't get around to it.