Much as I love opening up my computer, I'm thinking of cutting some filter pads to the intake fans to cut down on the dust and fur which can get into it.

Has anyone tried this, and with what results?

My personal box is a 4U rackmount case with a nice removable air filter tray -- you just pull it out, clean or replace the filter (a vaccuum works well if you hold on tight =)) and pop it back in. The dustier the environment, the more often you should clean it. Compared to cleaning out the inside of your case, it's an easy job.

An air purifier seems a little excessive, but the filters on those do last a lot longer between changes/cleaning =)