I have seen in many times , it has asked how convert the existing VB projects to VB.net. This msdn Link has the information about converting the existing VB project to VB.net.

Upgrading a Visual Basic 6.0 Application to Visual Basic .NET

VB to VB.net Conversion Wizard

But You have to be more carefull while converting that project.After Converting you have to check for validation, because the conversion process may leave some part