The About Visual Basic site contains several articles that detail different advantages of collections. If you're just moving up from VB 6, you might want to try reading this one:
The VB 6 Collection object
The Scripting Dictionary object
The VB.NET Hashtable object Explained!
Another "transition" article explaining the difference between VB 6 and VB.NET can be found at:
VB.NET: What Happened to Control Arrays!!!
This one has generated quite a bit of input from About Visual Basic readers and there are several sequels to the original article.

