If I understand your structure correctly, I think you are going to have many duplicates in your dev tree related to "tools" and "lib". Most likely these are external tools and libraries that might be shared by different projects.
Something that works well for us is:
solutionfile.sln
-src
--projectname
---config
---doc
---source files (structure representing namespaces)
-test
--testprojectname (usually, a test project per source project)
---unit test files (structure mirroing the structure in the source project)
-lib
--libraryname (containing the libraries)
-tools
