To find the uptime of a Windows server without uptime.exe:
Open a command prompt
Type "net statistics server"
The line that starts "Statistics since …" shows the date and time the server was last restarted.
(The command can be shortened to "net stats srv".)
On Windows 2008:
SystemInfo | find "Boot Time"
Returns:
System Boot Time: 02/03/2014, 00:06:12
(Windows Task Manager also shows uptime in Windows 2008)