I have a HP Compaq nc6000 laptop with the Mobility 9600 chip
getting everything to 'play nicely' was as simple as updating my kernel and getting everything the way that I wanted it and downloading and installing the ATI fglrx driver (note: you must download the regular card driver despite their warning about the chips/displays be custom for every manufacture) follow the directions to install the driver and run fglrxconfig to properly set-up X
note: THE CURRENT ATI DRIVERS ARE COMPATIBLE WITH X.ORG 6.7.X ONLY NOT 6.8.X
you might also want to google around and figure out what kind of LCD you have on you laptop to set the correct hori. and vert sync ranges
mine has a 14.1" SXGA+ display (1400x1050 native @ 60Hz, 63.98KHz hori. sync and 60Hz vert.) <- dunno if that will help you get rid of the "black bars" but you never know!