My mistake, you can only save the file project in vb.net.
In VS 2008 (C#) your only choice is to use windows explorer for the project.(copy project, rename, etc and add it to the target solution - of course you need to delete your old project in the target solution)
Note: VS 2008 (C#) only offers you rename (context menu in solution explorer) but it only rename the project in the same folder and it does not change the folder name