LOL, depends, as you might already know vb.net and c# sit on a framework. So it won't be as fast as win32.

dotnet is used by many professionals these days. If you want to design rapid GUI applications for windows, with the least amount of hassle dotnet is for you.

There is also java (GUI) as well, which you can use on linux mac and windows operating systems. I assume dotnet will follow suit (mono project etc), it's just java has had a massive head start.