Would you be open to using the Add/Remove inventory?

Office Professional 2007 brands: 'Microsoft Office Professional 2007'

So, you could create a sollection like the following:

SELECT r.Guid
FROM vResource r
LEFT JOIN AeXInv_AeX_OS_Add_Remove_Programs ar ON ar.WrkStaId = r.ResourceId AND ar.[Name] = 'Microsoft Office Professional 2007'
WHERE ar.[Name] IS NULL
AND r.isManaged = 1

If you have a different version of 2007, you can enter the brand from add/remove programs in place of "Microsoft Office Professional 2007".

Note: this is for the NS6 environent.  If you are using 7, let me know and we can make some changes.

RS