How to convert a web part project created in VS 2008 to VS 2010?
If I was starting from scratch, I would use the Visual Studio 2010 tools. But if you have an existing project using, say VseWSS, STSDev or WSPBuilder, I suggest you continue to use this. It should still work with Visual Studio 2010 after upgrading and possibly tweaking. I would not bother trying to restructure the solution to use the new deployment tooling in VS2010 unless there is some particular capability that is missing from your existing solution.
Please have a look at this question, it is a possible duplicate.