The various warnings about drivers, touchpad and wifi in these answers is almost amusing if not a little depressing. Remember the promise of the Linux Desktop? I remember giving ubuntu a good try in 2006, but after nightmares with xorg configs, flash, audio drivers and a clipboard that couldn't copy and paste across different applications I eventually switched to mac. It doesn't look like things have changed much in…
There has just been one thing I haven't been able to get working quite right and had to compile my own driver for, and that's a Logitech G13. It's different enough that generic drivers don't work, and rare enough and complicated enough that no one else had submitted drivers before.