.NET takes advantage of the best of all the technologies you have used to date, and it improves upon them. If you have an existing application in Visual Basic 6.0, you can attempt to migrate to Visual Basic .NET. There are several methods you can use to migrate, including simply reusing any COM components you already have developed, creating new components in .NET and using them from your VB 6.0 applications, or using the Migration Wizard.
NET allows you to leverage your existing code by providing a nice interface to your COM components. With just a couple mouse clicks within the Visual Studio environment, you can bring in your COM component and use it just as if it were a class library you developed in .NET.
The Migration Wizard will help you migrate from an existing Visual Basic 6.0 application to a VB .NET application. The Migration Wizard will convert many common elements of your Visual Basic 6.0 applications, but it cannot convert everything. You will still need to make many changes to your code by hand. You may also need to rewrite certain sections to take full advantage of new tools.
The Migration Wizard will also attempt to convert common ActiveX controls into .NET controls. In those cases where there is no equivalent, it will attempt to use the ActiveX control on the Windows Form (WinForm) in .NET. Many ActiveX controls will work on a .NET WinForm, but there are no guarantees.
Reasons to Migrate
The .NET Framework includes many interlanguage integration features, such as inheritance, debugging, common data types, and Windows and Web Forms. Creating Web applications has never been easier, and cross-platform capabilities using XML Web Services makes communication with non-Windows applications a breeze.
The installation and removal of programs is much easier now that .NET applications no longer have to be registered like previous COM applications did. Installations can be done by using a simple copy command, and uninstalling is as simple as deleting the files. Of course, this assumes that the .NET Framework and the CLR are already installed.
SHOULD YOU REWRITE?
In most cases, you might want to leave your older applications in their original language. But if you find that an application that started out as a departmental-level application now needs to be an enterprise-wide application, you might want to rewrite.
The Internet has changed society and business as we know it. You now need to think about all programs as being "global" and "distributed." Doing this with the tools before .NET was not easy; in global distribution cases, you will probably want to migrate your old applications. In most cases, you will probably find that you can remove large sections of your code and replace them with just a few objects in the new .NET Framework.