I have the same problem, I made the new directory, and I put the desktop file, but Cinnamon in Ubuntu 13.10 still shows the stupid Windows logo, I was searching in others forums but this one was the closest to my problem.
I'll show you my desktop file for Microsoft Windows
[Desktop Entry]
Version=1.0
Type=Application
Name=Microsoft Word 2010
Comment=
Icon=word.png
Exec=env WINEPREFIX="/home/larry/.PlayOnLinux//wineprefix/Office2010" wine C:\\\\windows\\\\command\\\\start.exe /Unix /home/larry/.PlayOnLinux//wineprefix/Office2010/dosdevices/c:/users/larry/Start\\ Menu/Programs/Microsoft\\ Office/Microsoft\\ Word\\ 2010.lnk
NoDisplay=false
Categories=wine-Programs-Microsoft Office;
StartupNotify=true
Terminal=false
StartupWMClass=WINWORD.EXE
Encoding=UTF-8