Oh, right - dust removal.
Mostly, if I'm vacuuming the office, I'll pop the bezels of the two PCs there and use the brush attachment to remove any built up dust from the fronts of the now-exposed heatercores.
I took one PC out to the garage (had had a RAM failure, so had been digging around in there anyway, trying to figure out what was wrong) and blew it out with compressed air. It was surprisingly "not that bad", other than dust built up on the leading edges of fans. I guess heatercores make decent dust filters...
