The .NET Framework 3.5 SP1 included a bunch of new features, but as a Service Pack it also included a number of bug fixes and many improvements. These fixes included all aspects of the .NET Framework from ASP.NET to WPF and the CLR. Will the .NET Framework 3.5 SP1 break my 2.0 apps? Almost certainly not. Why Not? Remember that 3.5 (and 3.0 before it) all have the 2.0 CLR at their core. If you want excessive detail on this, I've got it . Because the 2.0 CLR is the engine underneath and 3.0 and 3.5 are primarily additive*, there's inherently high application compatibility between these releases. Realize that 2.0, 3.0 and 3.5 are not different products, no matter what anyone says. They are not different "Side By Side" releases...(read more) ...
Go to the complete details ...