I recommend to avoid Visual Basic at all costs, unless you expect to use VBA (in MS Office) or VBScript. VB.NET is a lot closer to other modern languages like C#, and Java.
- VB.NET is a modern language. VB6 is compatible with old 1980's BASICA and QuickBasic
- VB.NET is an object oriented language (VB6 has partial support)
- The .NET framework is vast and organized, VB6 ActiveX components are few, and old
VB6 has tons of shortcomings: no exception handling, no array constants, no threads, 4-byte aligned structures (fast, but incompatible with many Win32 and DLL structures), IDE (Visual Studio 6) is nearly impossible to install in Vista/7, highly incompatible (VB6 to .NET converter rarely works), obsolete installer, no resource editor, etc.