Here's a hint. If you are upgrading from 3.6 to 4.0, its just easier to drop the database and let 4.0 create a new one and start from there. ESPECIALLY if you are changing SRP Identifier.
My process: exported users, stopped SQL services, copied the database files out, uninstalled MSDE7, uninstalled BES 3.6, installed SQL 2000 (substitute with MSDE 2000), installed BES 4.0, added select beta/test users (although you could import users at this point).
The entire process took 20 minutes or so. I don't think I left out anything. I'm not much of one for upgrading. If you have IT Policies in place, you can add in steps to export and import them at some point in there as well.
Just keep in mind that the only information you will lose by losing a 3.6 database is the License information and IT Policies. nothing more.
Hope that helps for any future upgrades.