Want to know how long has your Windows XP system been running is?
Click Start > Run and type “cmd” (without the quotes) to open the command prompt. At the prompt, you type:
There you’ll see your system information. Scroll down the list to the line where it says System Up Time. This line will tell you in days, hours, minutes and seconds how long your computer been running.
Note: This command works in Windows XP Professional. If in Home Edition you type:
net statistics workstation
Hope this helps!