Mark Russinovich at www.sysinternals.com has released freeware utility PsUpTime which displays how long NT has been running. Useful to Windows NT admin.

It uses the Performance Data Helper library to easily read the System Up Time performance counter on the local machine or the machine you specify by name on the command line. Full source code is included and I've included a copy of PDH.DLL, a Microsoft DLL that comes with the SDK. Contrary to what Microsoft's documentation implies, it doesn't appear that this DLL is included in a standard NT 3.51 or 4.0 distribution (it is in NT 5.0).

New Riders has good NT texts.