There is no such things as “hash cracking”. Better than learning VB.NET for UDP flooder and such lame things, learn something that’ll be really useful ( like what are hashes :p )
I’d say there is no specific language for hacking, so yeah you can do things with VB.NET, but without actual knowledge, you won’t do anything.
But I’d recommend you to learn other languages and to do some real codes ( try capatcha levels ;) )
Good luck!