Ok.. I have repro'd this and after removing office 2007 pro trial, Office
home and student edition still worked fine. The important thing here is that
Windows detects both installs as seperate products. The Office pro trial will
not "upgrade" the home version, but in fact install side by side.
Here are my steps.
Installed Office 2007 Home and Student edition
Activated product.
tested. (worked fine)
Downloaded Office 2007 Pro Trial
Installed product (During install put all features to not available except
Access and tools and shared features)
Installing this way DID NOT upgrade. Windows sees office pro trial and
office home and student as two seperate products.
Activated the trial.
Testing word from Home edition, and Access from Pro trial edition. Both
worked as expected.
Uninstalled Office Pro Trial
Testing Word and Excel from the Home and student edition.
The Home and Student Edition still works successfully.