to change it you would need to change the project name in solution explorer, click on it once so its higlighted and then click on it again to rename or rightclick and then select rename, also the solution.
Next step isto click on project again and rightclick, this time select properties and change the assembly name and default nasespace giving them the same name as your project name. Click on assembly information and do the same again, you can keep the version number the same.
obviously now you need to go into the classes and change the namespace to the same namespace in the poperties default namespace.
build the project, it might fail becuase it cant find the correct files. Just close the project.
Go to the folder location where its saved and rename the folders to the same as your project name. Open up the project by doubleclicking on the solution file.
It will say it couldnt open up the files, thats becuase its looking up for the old names whats fine :), you need to remove the greyed out project in solution explorer by rightclicking on that file and click remove and then right click on the solution file and select add then exsisting project, goto the folder where the project is saved and add the project with the extension .csproj.
now you should see all the files and folders back in with the new names, build the project.
The last part you need to do is change the guid for the wsp. In visual studios goto tools and the select create GUID, select copy and close it.
Goto the folder where the project is saved on your harddrive and go into the project folder and find a file called solution.txt and open it, replace the guid with the new one. Save and exit :). Or open it in the project it should be called the same :), just replace the guid!
That should be it, You need to build the app again, then build in wspbuilder and deploy :)
hope it helps :)