Looks like my imac is taking off,
Apps open: Safari, HP Director (scanner) and XRG
CPU T-Dio 64.7°C
Hard drive 43°C
CPU fa 5600 rpm!
Hard Dr 2000 rpm
System 3207 rpm

I took the cover off and vacuum quite a good amount of dust. So thought that that could be the reason but the lectures above are already after removing the dust. Didn't take any of the fans off, just did a superficial cleaning as recommended: http://docs.info.apple.com/article.html?artnum=58270

Second lecture:
Apps open: 10 + Finder
CPU T-Dio 72°C
Hard drive 45.5°C
CPU fa 5600 rpm!
Hard Dr 2000 rpm
System 3207 rpm

No vibrations but definitely noise.

Does it looks like doing a deeper cleaning of fans to bring down the temp -> rpms?