How log your pc has been running

You can easily know UPTIME of pc

Just Click on Start button then Press Run and type cmd to open command prompt.
At the prompt, type systeminfo

Scroll to the line that says System Up Time.

This will tell let you know  how long the system has been up in days, hours, minutes and seconds.

Note: This tips only works in XP Pro but not in XP Home.

You can also know other informations like net statistics atc at Home also. The first line will tell you the day and time that the system came online.

so why do you wait........ take a look on your system uptime.