FYI, while all PC setups do not work well with sleep or hibernate, you can set WMC to wake your PC to make a recording...my PC is always on...the cost for elec is not too much for me and I prefer not to start and stop electronics too much. With Windows 7 my CPU (the power hog in most systems) is literally at 0% when I am not using it anway and I do turn off my monitor. Plus, I use it all the time

It's on at night for WMC optimization tasks, backups, nightly AV Scans, updates, scheduled tasks such as disk defrag...that works well for me.