Microsoft has a network install utility called "Network Installer" in which you can preset installation settings. In the end you get a command line of some sort. For the "CHECK FOR OFFICE" routine maybe something like :
;Check for Admin Privs

IF INGROUP("\\@WKSTA\Administrators") OR INGROUP("Domain Admins")

;Check Installation Exists

$ReturnCodeO2000 = Existkey("HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{00010413-78E1-11D2-B60F-006097C998E7}")
IF ReturnCodeO2000 <> 0
SHELL "<what ever the Network Install program says>"
END IF

This could/should work fine. We use a similar script with WINSTALL Installation packages.

Gillez