As I've noted that SQL Server 2008 is now a supported version, and we're also running into the 4GB file size limitation in the 'Express' edition after adding the NetFlow module...
What about moving up to the 'Workgroup' edition of SQL Server 2008 rather than the 'Standard' edition? It has all of the functionality of the 'Express' edition but without the restriction on database size. (and is a good deal less expensive)
Figured it best to ask since the 'workgroup' edition is not shown as one of the 'supported' options.
-jim