There is a Patch 3 integrated installer available through the "My Downloads" page - in any case you should be using Patch 3 with Win7 as it resolves an issue with "anti-virus disabled" type alerts from Windows Security Centre.
Not sure why it's refusing to install on some machines. Do you have a log you can post (IIRC, it should write a log out to the TEMP directory during the install)
Key in your Grant number and click on the McAfeee Virus Scan Enterprise 8.7i. You will able to download the VSE 8.,7i installer file with P3 included. Please try installing that and revert how did it go.