I have several machines. My workstation at my office has not been rebooted in 70days, without a problem (did I mention it runs linux?). I use this machine 7-14 hours per day m-f.
My home workstation has windows on it & I reboot it as needed. sometimes once per week, sometimes once per month. I use it so infrequently though, that it really just sits there & runs most of the time. Defrag weekly automatically with
autodefrag. This machine runs windows xp pro.
I also use an ibook a lot. I reboot it whenever there is a software update that insists upon a reboot, never anytime else. Current uptime is 16 days (20-25 is probably average), and I never have to defrag the disk. I just open it up, use it, and close the lid (it goes into sleep mode) when I'm not. Never takes more than about 3 seconds to wake up, and always does whatever I want it to. I use this machine 1-7 hours per day.
So yea, whenever I'm not working on my dsm or playing with
Turbo, I'm strapped to a computer, doing shit for someone, somewhere.