Migrating to Win Server 2003

My production ASP.NET site is running on Win 2000 and IIS 5. I'd like to
migrate this to Win 2003 and IIS 6. I also have 2 QA web servers, and Build
server and each developer has a web server all running Win 2000 and IIS5.

My question is can I keep my developers and Build box running Win 2000, and
upgrade one of my QA boxes to Win2003? Will the DLL I built in Win2000 run
properly on Win2003 and IIS6. My site is using .NET framework 1.1 SP1.

If I upgrade my Build box and my developers to Win 2003, will the DLL run OK
on Win 2003?

Any good links on problems with migrating to Win 2003 and IIS6.

Thanks,
Grady