ComputerBB

Well, it is finally out.
You can download DirectX 9.0c here.

I already downloaded DirectX 9.0c for my system.

I know this sounds really newbish, but what are the advancements since direct X 9.0B?

The letters generally mean that they've taken out something that was in previously but was illegal to put in for some reason or another. Like Windows XP SP1a is SP1 minus some of the monopoly related issues.