I had the motherboard in, and up and running in a couple of hours, and i slowly worked on all the small things. I would say it took me quite a few hours, but there is no way to say exactly how long it took.
It was even cleaner before, I had a Sonnet SATA card, and the SATA cable ran behind the motherboard and couldn't even be seen. Because I am selling it i took out the SATA and put a PATA back in, leaving an ugly ribbon cable running straight down the middle. Luckily the cable is flat and doesn't obstruct air flow.