Using VB.Net or C# is same same, you can do the same on both languages, don't worry about that.
You can use same libraries, same .net, works on same platforms and so on.
I have used vb6, vb.net in the past, but converted to C# around 2003, but that is mostly because I like the syntax better, and working with peers who use same language.
Learning C# is an good idea, depending on the teams you are working with, but if you are working alone, you should chose what is working for you.
You can download Reflector from
http://www.red-gate.com/products/dotnet-development/reflector/ with this tool, you can look at .net compiled dll's, and you can chose to show the decompiled code as C# or VB.net, which can be a good way to learn also.