Forums will be making significant UX changes to address key usability improvements surrounding search, discoverability and navigation.
To learn more about these changes please visit the announcement which can be found
Validation requires no validation number. Installation and activating Vista requires product key. If your new computer has Vista as operating system, you should have the COA (please see http://www.microsoft.com/resources/howtotell/en/coa.mspx for info on COA). The COA includes the 25-character product key.
If your Vista has been activated, you need to run validation to take advantage of the benefits of Windows Genuine Advantage Program and to check whether your Vista is authentic.