I have an old laptop that I installed Ubuntu 12.04 on for a family member. It's an HP xt3000 with 748MiB RAM and 60GB disk. I had to install with non-PAE support and nomodeset if that's relevant.
Everything seems to be working fine with Unity 2d, although a bit sluggish to launch applications (probably need more RAM?). The main show-stopper is youtube video performance with is very choppy.
Any thoughts whether additional RAM will fix this too, or would he proprietary fglrx drivers be a better bet?