HUAWEI Smart AX MT 841 Driver
You do not require any driver if you connect modem thru Ethernet (as suggested by Gowtham.)
However, if you need to connect thru USB, then the following file may be of helpful to you. It is working for XP but I don't know about Vista.
http://rapidshare.com/files/61340319...USB_driver.zip
Inform whether it could solve your problem.