If you just want to test a version of UAE on your machine. I would goto amigasys as they have a bootable linux USB stick download just for E-UAE. As for Ubuntu, meh I would use Mepis if I were you. Ubuntu is ok, but it gets more like windows everyday ie bloaty it also uses a lot of test software. Mepis is based on stable and is just what it says. Anyway amigasys linux live usb stick download:
if you grab this script it will install the graphic drivers for you, as long as its supported by the xorg version.
The sgfxi script automatically downloads and installs the kernel headers and every thing else it needs. This script downloads the binary graphic driver installers from either nvidia or ATI, prepares system, installs, then sets up xorg.conf, all in a fairly clean, reasonably intuitive way. Plus it updates itself so any new drivers released will be installed. Finally, sgfxi allows you to easily switch between proprietary non free drivers like ATI's fglrx and nVidia's nvidia driver and the free xorg drivers.
sgfxi can be run with numerous options. Enter sgfxi -h to see all the options and check the sgfxi Manual at the documentation links below.
Handy program for all Linux users. Got me out of trouble plenty of times, you can even restore the old drivers if you mess up.