i got a solution for u
1- just install the software of the modem ( which is automatically starting when inserting the modem into USB )
2- then go to c:/Program Files/vendor name/Driver
note: replace vendor name with the name of the card vendor e.g. ZTE
3- you should find the drivers ( INF files ) inside winVISTA
4- right-click on My Computer and choose Manage...
and then choose Device manager
5- search for the 3 devices
of the modem ( they will have yellow marks as with any device without drivers )
and right-click on each of them and choose Update driver software
note: the USB modem has another 2 devices
related to mass storage device stuff , ignore them!
6- now follow on but choose to locate the driver manually , and choose Let me choose the driver
then locate the files on the C: partition and follow on.
in case u didn't find the files download them from the following link: http://rapidshare.com/files/286868138/ZTE_MF637_HSUPA_drivers.zip