The primary languages are C# and VB.Net. VB.Net should be an easy transition for you with VBScript, I personally prefer C#. If you have JavaScript experience you may be able to take up C# pretty quickly as well (capitalization issues in the beginning).

It's all about getting familiar with the libraries and namespaces. The syntax should not be that difficult. Some benefit of ASP.Net is the code behind, richer language, MasterPages. No more interspersed <% %> in your html code. I would shoot myself if I had to go backwards.
BTW, I started with VB and then ASP and now use C# so I have followed the same path.

Good luck...