Think this issue has been addressed a number of times.
Turning it on and off on a regular basis can shorten the life of the components (ie. 10 - 15 times a day)
if your turing it on and off that much, doesn't it make sense to just leave it on?
My computer stays on 24/7/365. Only time it ever goes off is if i'm upgrading, or tweaking.
If you don't use your computer that often (what are you doing posting on anandtech?)
I think for 99% of the anandtech board members, if your system can hack it.. leave it on 24/7
Dr Cool