Just installed ubuntu 8.04 as my 3rd OS on my 3.5-year-old laptop. The installation went quite smoothly. Even my bluetooth dongle works out of box. I can open my N95's directory quite easiy and copy back and forth files.
The only annoyance was that the firefox 3.0b5 didn't work with the Adobe flash player 9. However, today I manually installed 3.0 rc1 and flash player 10. It works like a charm!