My brother has a gateway laptop and it works well.
The only thing was that it came with a restore partition and it didn't work! No cd or anything, they just had it so you turned on the computer pressed f11 and it would go to the restore screen. He tried doing this (wanted to clean out the computer) and it froze in the middle!!
I installed winxpsp2 pro on his computer and now it runs beautifully. No problems since then. It's a fast smooth laptop for pretty cheap.
I would never buy a prebuilt machine... but for laptops I know they're alright (or atleast in this one case... after that small problem)