I am using a Dell Laptop with embedded mobile broadband chipset (Dell 57xx) on Windows 7. During install it goes all the way and then it starts to roll back.
A new compatible connection manager for the 57xx (older than 5720, e.g. 5700 or 5705) device for Windows 7 has been published/released and is available at the following location:-
For DW5720 Verizon, the download
For DW5720 Sprint, the download
For DW5720 Telus, the download
Devices Just Work, Mobile Broadband