In linux, punching in uptime provides you with how long the system was up without a reboot. But how to do this in Windows? There is no real indication to be found anywhere. Here's how.

The uptime can be found using the command prompt.

Do a start -> Run, punch in cmd and hit Enter (like you normally would).
Type in the command:

net statistics server

(and hit Enter).
Find the line that starts with Statistics since...: it will tell the time the server was up from.

Note that you could shorten the commands like so:

net stats srv

The above has been tested with: Windows 2000 (all versions),   ...