You should be able to get the fonts directory location from the
following registry location:

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell
Folders]
"Fonts"="C:\\WINDOWS\\Fonts"

Jesse Houwing

If anyone else needs this:

// get it from the environment
        String dir =
System.Environment.GetFolderPath(System.Environment.SpecialFolder.System);
        dir += "\\..\\fonts";
        dir = System.IO.Path.GetFullPath(dir);
       count += registerDirectory(dir);

        // get it from the registry
        Microsoft.Win32.RegistryKey regKey =
Microsoft.Win32.Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders");
        if (regKey != null)
        {
            Object obj = regKey.GetValue("Fonts");
            regKey.Close();
            if (obj instanceof String)
            {
                String dir2 = System.IO.Path.GetFullPath((String)obj);
                if (! dir.toLowerCase().equals(dir2.toLowerCase()))
                    count += registerDirectory(dir2);
            }
        }