If you're using nVidia drivers, I would suggest just simply downloading the nVidia package in synaptic, restarting X, and then using System -> Preferences -> Screen Resolution for that...which should be all you need, as with the proper drivers, 90% of the vid cards out there will be properly detected.
If you're using ATi, my condolences. It's not easy to configure, but it can be done.
However, if you are looking to get all the "extras" working in ubuntu, might I suggest:
https://help.ubuntu.com/community/RestrictedFormats
Cheers,
Lord Ghost