RE:
DES and TripleDES

What's the deal with the Initialization Vector (IV) properties of the DES and TripleDES classes?

Do I need to keep a copy of it alongside the key?

I want a very simple way to encrypt the contents of a MemoryStream and write the result out to a file.

Does it matter if the IV is different each time I encrypt / decrypt data? As long as I have the key it should be fine right?