Do you want to work under Visual Studio 2010 and your project is currently working under VS 2008?
All you need to do is to to convert your projects into a VS 2010 Version.
However there could be a small problem that we are going to solve: not all projects can be converted, and I am speaking about Web Deployment Projects. In order to make those available for VS 2010 you will need to download and install the "Visual Studio® 2010 Web Deployment Projects - RTW".
Now if you want to migrate your project from a .Net 3.5 to .Net 4.0 then you can face an error like this:
"Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive."