<p>Basically I have a bunch of unmanaged VC++ static libraries. And the VC++ GUI application which uses those and it is based on MFC. 
The goal is to replace the GUI app with the one done in C# instead but using all the same static libraries.
The question is if this even possible, and if yes, then what is the right way to accomplish that?</p>

<p>Suggestions, anybody?
Thanks. </p>

Yes, it is possible using C++/CLI for managed C++ code.  You would write a C++/CLI WinForms app and simply link in your static lib as per normal.
However, if there is a lot of tight coupling between the GUI code and the libraries then this can get a bit messy.  You will need to worry about converting some data types between the managed and unmanaged world, particularly strings.  If you need to pass managed objects/arrays
There is a good introduction on
Wikipedia
and lots of documentation on
MSDN
.