It’s sometimes useful to know how long Windows has been running. With most Windows versions, including XP and Vista, you can find out when the system was most recently started by opening a command prompt window (Cmd.exe) and entering this command:
You’ll get a screen full of information about your computer (model number, CPU, memory, and so on) and your current Windows installation, including which version you’re running and when it was originally installed.
In the opening block, on a system running Windows XP, you’ll see System Up Time, measured in days, hours, minutes, and seconds, as shown here:
On Windows Vista, this block of information includes the System Boot Time (the date and time when the system was last started), but the System Up Time value is not shown here. Instead, you need to go to the Performance Tab of Task Manager and look in the statistics block at the bottom right corner:
In the case of Windows Vista, the measurement of up time does not include any time when the system was sleeping or hibernating.