It's always a balancing act between moving forward with technology upgrades while not abandoning products which are still being used. At ACS, we try to bridge as wide a span as we possibly can, in order to accommodate the needs of all clients. Sometimes, however, changes need to be made.
Therefore, starting at Advantage 11r1, the minimum system requirements will be 64-bit versions of Windows Server 2008 and SQL Server 2008.
This shift allows us to prepare for supporting a scale out (clustered application server) deployment model. Requiring 64-bit OS and SQL also supports vastly greater system resources, particularly memory. This is important for running Advantage, since we typically recommend that 10-20% of the total database size be available for caching.
Typically, ACS supports the prior two releases of each product (currently Windows Server 2008 & Windows Server 2008 R2 and SQL Server 2008 & SQL Server 2008 R2). Since Microsoft is no longer providing mainstream support for Windows Server 2003 and SQL Server 2005, it would be increasingly difficult for ACS to support new releases of the software on those versions. Of course, we will continue to support earlier releases of Advantage using those versions.
Contact your account manager if you have any questions.