SQL is for the most part a standard syntax - especially between the Microsoft DB products. Nothing in your code should have to be changed.

However you might want to consider using stored procedures aftter you complete the upgrade:
http://databases.about.com/od/sqlser...dprocedure.htm

Faster and are really great for security, especially avoiding injection-attacks:
http://msdn.microsoft.com/msdnmag/is.../SQLInjection/

If you need any help with the configuration or change-over we're only a post away!