That might be the reason my fan is noisy. I mean its not real loud but you can hear it revolving. I've only had this iMac for a few months and I haven't done anything except open up the user accessible slot on the bottom to install an airport card. The only thing I know is if you do open it all the way up you have to reapply thermal paste, which sounds like a mess. I guess eventually I'll need to open it up and clean it out good but it does alright right now.

The only real problem I had on this machine was when I used a USB wifi dongle (before my airport card shipped) and there was times that the system would slow to a crawl or freeze. Never had that problem since I got rid of it. Websites seem to load pretty decent, I haven't had any real problems with that. I think if I bump up the RAM to 1.5GB it'll probably help things out considerably as well.