Just a short addition:
When I updated my previous version of the TDM-Add-in on my Windows Vista PC the icon for the TDM-Add-in in Excel was gone.
If this also happens on your PC try the following:
After installing the Add-in search for the Excel.exe in the Windows program files folder (e.g. C:\Program Files\Microsoft Office\Office12\), perform a right mouse click on it and select run as administrator. After that the Add-in icon should show up again even when you launch Excel the ordinary way.
Regards,
ThomAC