Soldato
Mine wouldn't fit on my desk, not that i'd even want it there anyway. Buy a case with dust filters on every intake and vacuum them once a month and its fine on the floor. If i had a good looking mATX system and a bigger desk i might consider it. I'd probably still put it on the floor out of the way though.
Thats fine if you have positive pressure in the case, but a lot of people dont, so unfiltered air will be getting sucked in all over the place. Often see people with the top 2 fans as exhausts and the rear fan/s as exhaust, plus the psu flipped over so thats acting as an exhaust. Then some also have a gfx card that exhausts the air out of the case. Then they wonder why their case is full of dust.
Plus most filters do naff all anyway. The ones fitted to my Corsair 650D are useless.