they is a very good RedBook to migrate from SQL Server to Informix. I think that SQL Server is such a good and popular product, and tons of books should have been written about this subject.
You'd better try to get info in the Sql Server Forum
You will discover soon all the "advantages and joys" of downgrading to SQL Server :-)
Sorry for being sarchastic, but I still do not understand why some decision makers persist on losing all the advantages of Informix ( stability, performance with equivalent system capacity, robustness, low total cost of ownership...), for more expensive systems, less stability and availability, less performance and higher TCO.
Would this system be eligible for the free Edition Informix Innovator-C instead of spending money, time and reliability on such a migration ?