A trick for all geeks who would like to know how long since they haven't shut down their computer.
1. Go to Task Manager (Ctrl+Shift+Esc brings without UAC popup).
2. Go to performance tab.
3. In the system Information you can check out the uptime in the format Day : Hour : Minute : Second.
You can track your computer uptime easily now.
"Windows 7 Tips: Find Computer Uptime"
Reference : www.WindowsVJ.com