I couldnt get ACT 17 to work on SBS 2011 with SQL Server Express 2014. I followed the instructions to install ACT7 instance - http://kb.swiftpage.com/app/answers/detail/a_id/38099/~/how-to-manually-create-the-microsoft-sql-ser...
But ACT failed to connect to any database or create a new database. It appeared it couldn't connect to the SQL server.
Uninstalling and reinistalling the previous version of ACT (with SQL 2008 express), and applying the ACT17 upgrade, everything seems to work OK. (I havent tried the web version again yet).