Just a small detail, but maybe it makes sense to remove the “Make New Folder” button from the os native folder chooser when not saving. At least, I couldn’t think of a case where you might want it.
This can be done by setting the BIF_NONEWFOLDERBUTTON flag (0x0200) for BROWSEINFO.ulFlags in combination with BIF_NEWDIALOGSTYLE. The flag is only supported from version 6.0 of the shell dlls, but I’m guessing setting it on version 5.0 won’t hurt. The flag is not defined in the shlobj.h that comes with MSVC 6 though.