This check is a variation on an existing check for Anti-Virus definitions.
In this version I have removed the checking of a second server and instead allowed you to specify the age of the definitions in days before returning a warning or critical check as well as returning the age of the definitions as Performance Data.
I have also updated the script to handle the different registry paths between 32-bit and 64-bit versions of Symantec Anti-Virus or Endpoint Protection
Save the script to your NSClient++scripts directory and then add the following line under the [NRPE Handlers] section of your NSC.ini file
check_av=cscript.exe //NoLogo scriptscheck_av.vbs /W:$ARG1$ /c:$ARG2$
cscript /nologo check_av.vbs -w:< days > -c:< days >