>Hi,
>
>I have a project/application I developed in ASP.NET 2.0 using VS 2005. I need to leave this project and maintain it but to add some features for new customers. So I will need to duplicate this project in the next version of VS. I would like this project to work with .NET 3.5. I have not kept up with all the new version of VS MS published. So my question is, what version of VS should I purchase?

I think you're mixing up the VS studio version with the .NET Framework version?
Sounds like you should go for VS2010 but set the projects to target .NET 3.5.....