my side panel is generally always off, because it's a pain to put it on...dust does collect quite a bit more though, but technically the side panel on is better assuming you've got good fan placement and air flow.
Amd2800 - quit being an arrogant douche. What kind of assanine statement is 'learn about computers before you ask for help'.....that's just retarded....like he said, he obviously is coming here to learn