Should you set all the objects to null (Nothing in VB.NET) once you have finished with them?
I understand that in .NET it is essential to
Karl is absolutely correct, there is no need to set objects to null after use. If an object implements IDisposable, just make sure you call IDisposable.Dispose() when you're done with that object (wrapped in a try..finally, or, a using() block). But even if you don't remember to call Dispose(), the finaliser method on the object should be calling Dispose() for you.
I thought this was a good treatment:
Digging into IDisposable
and this
Understanding IDisposable
There isn't any point in trying to second guess the GC and its management strategies because it's self tuning and opaque. There was a good discussion about the inner workings with Jeffrey Richter on Dot Net Rocks here: Jeffrey Richter on the Windows Memory Model and Richters book CLR via C# chapter 20 has a great treatment: