On my XP I couldnt locate the file thru the use of Start=>Search and locate
the file opa12.dat.
However i did find the file via:
1. Click Start, click Run, type %AllUsersprofile%\Application
Data\Microsoft\Office\Data, and then click OK.
2. Locate the Opa12.dat file in the Data folder.
3. Right-click the Opa12.dat file, and then click Delete.
Important Do not delete the Opa12.bak file.
4. Close the folder.
5. Start a 2007 Office program to start the 2007 Office Activation Wizard.
Note When you uninstall the 2007 Office product, the license file is not
removed. Additionally, the license file is not overwritten when you reinstall
the 2007 Office product. By deleting the Opa12.dat file, you force the
license file to be recreated.
(info found in the MS Knowledgebase)
After that i started outlook2007 and the activation wizard was prompted, and
i was able to activate. The trial works now!