While I know this may always not be accurate, open Windows Explorer and
drill down to C:\Program Files\Microsoft Office\2007. With Details (click
view, details) turned on, the earliest date listed for any of the folders
should be the date installed. Works for all versions of Office on my
systems but not some other software (my antivirus and photo editing software
shows dates copied from the installation CD.)
On the laptop that I am using currently, I know I purchased it on 6-12-07,
installed Office 4.3, '97, 2000, 2002 (XP) on 6-13 and Office '03 on 6-14
and Office 2007 on 9-24-07 via the dates showing and these are accurate
installation dates.
