Redgate SQL Compare vs Visual Studio 2010 Premium/Ultimate database project
I tried to use the VS tool yesterday with my production SQL 2000 instance, comparing to my dev 2008 instance, and it refused to work with anything prior to SQL 2005.  Red Gate definitely does not have such a restriction.  It even works reasonably well (not 100%) with another database we have that runs in 6.5 Compatibility Mode.