This Huawei U8100 USB Driver and PC Suite is taken from the phone storage. When you plug the USB cable from your computer to your phone, you will find this driver and PC Suite in a new CD Drive on your computer.
This driver also used if we want to install ClockworkMod recovery to a computer that have install this driver before. It won't be necessary if your phone storage can be read and access from the computer. But it will be very important if your computer cannot access the phone storage and you have to install the driver from outside the phone.
Additional Informations:
Default Huawei U8100 USB Driver + PC Suite Download Link
Install ClockworkMod Recovery
MyPhoneExplorer: PC Suite For Huawei U8120 ROM