Have you verified it was installed by going to your Control Panel/Add Remove Programs? Do a "Search" in your computer for "Desktop Manager" and see if it turns up and where.
Sounds like something went wrong with the install then.
Have you tried installing the older version from the CD that came with the phone and see if that works? If that works, just try downloading the new version again.
My phone didnt come with a CD it was used. but when i plug in the USB it charges fine. and it connects to my computer fine.. its just a problem with DM
Did you maybe install Device Manager instead of Desktop Manager? Go download again and make sure you are downloading Desktop Manager and not Device Manager.
what JC said. It sounds like you downloaded the Device Manager package, not the Desktop Manager. This will give you the drivers, but not the interface.