Oh, it seems perhaps you are starting Studio Express by opening the .exe file directly? Don't do that; you'll want to use a shortcut or batch file. The shortcut that the installer creates normally says "Start in" %HOMEDRIVE%%HOMEPATH% (e.g. C:\Users\yourUserName\).
So you can either set the working directory (via "Start in", for a shortcut, or cd for a batch file) before launching the Studio Express executable (and the workspace directory will be named workspace-studio under that) or you can add the -data option (with the full pathname to the workspace directory itself) to the command line that launches Studio Express. Either one will work as long as you have create / write access to that location so the metadata / project structures can be defined.
As I, and others have mentioned, the installer program cannot create a shortcut so I had to create it manually. The installer program gives an error message.
I'll try later this morning