If you want to leave your computer on all the time, the please consider going to
www.grid.ord and consider using your computer to aid in finding treatments and/or cure for CANCER.
This research program runs in the background and can be setup even using a dialup connection to 'AUTOMATICALLY" (without you even having to be there) retrieve and send computational work units to and from the
www.grid.org server. There is also an addon automatic dialer program which can be downloaded and installed to perform the dialup function.
I currently have 5 computers working on this 24 x 7. If you consider doing this, I highly recommend having a good UPS on all of your systems, so they can be properly handled when you are not at home.
As someone else said, if you are going to leave it on all the time, why not make some good use of the CPU processing power.
Thanks & good luck.