hi mcm,
With ASP.NET, developers can choose to create the server-side code for their Web pages in a myriad of languages. The most common languages that developers will choose, will likely be VB.NET or C#. (There are a number of other languages one can choose to use, from Perl.NET to JScript.NET to COBOL.NET.) Of the many ASP.NET articles and code examples that exist on the Web, it seems that while a slim majority of them are shown VB.NET, a good number are written in C#.
What language is the "best" language choice? If you are a VB wizard, should you take the time to learn C# or continue to use VB.NET? Are C# ASP.NET pages "faster" than VB.NET ASP.NET pages? These are questions that you may find yourself asking, especially when you're just starting to delve into .NET. Fortunately the answer is simple: there is no "best" language. All .NET languages use, at their root, functionality from the set of classes provided by the .NET Framework. Therefore, everything you can do in VB.NET you can do in C#, and vice-a-versa. The only differences among languages is merely a syntactical one.
If you are more familiar with Java, JScript, or C/C++, you may find C#'s syntax more familiar than VB.NET's. If you've been doing VB for the past five years, there's no reason to think you have to now switch to a new langauge (although you should always look to be learning new things).
What if you have an ASP.NET Web page written in C# that you want to convert to VB.NET, or vice-a-versa? As aforementioned, the languages only differ in their syntax, so this translation, while not usually trivial, is still fairly striaghtforward, and can be accomplished systemmatically. For information on the syntactical differences between the two languages, be sure to read: From VB.NET to C# and Back Again.
Happy Programming, with whatever language you choose!