Currently you need at least the standard version of VS2005 or VS2008 to run NORMA. We are hoping that Microsoft will add one module that we requested to the free Express version of VS that would allow NORMA to run on that, but so far no decision has been made whether that will happen.
In addition to VisioModeler, which is freely available, the ORM Source Model solution in a high end version of Visio provides good support for ORM 1. As Ken indicated, NORMA supports the ORM 2 notation, which is significantly better than ORM 1. NORMA offers some features not found in the other products (e.g. mapping to non-relational targets, truly live error detection, context diagrams etc.) but its current relational schema generation lags a little behind the other products in terms of completeness of constraint code generated, incremental support (e.g. update scripts) and the number of DBMSs for which we provide reverse engineering. That said, we are actively working on major enhancements to NORMA and hopefully you should see some of these deficiencies addressed in the near future.