Mark
on the Optiplex was the full range of resolutions on the graphics adapter which needed to be entered manually. That may freak out a beginner but most of us who've used Linux for a while wouldn't find that too difficult a task.
That's the issue that i have with ubuntu when they removed the 8.04's Screens & Graphics and weren't able to replace it with the package that Fedora and other distros had working. It didn't work for about three releases.
I've just had a surprise having tried to load Mepis on a reasonable fast machine with an nvidia card - and it's worked fine on an old P3. All i'd say about ubuntu and mint is that they sit on a lot of hard work by debian [which is what i may switch to shortly].
james