Determine uptime on Windows machine

This is quick way to determine when your Windows machine had a reboot.
Open a command prompt and type in the following command

net statistics server

The result could be like

Statistics since 18.03.2011 08:19

In Windows 2008, Vista, 7 you can get the same information by starting the task manager and take a look at the Performance tab. You will find Up Time under the System field.