Open to a directory on your HD and go to my computer rigth click got properties. select modem (if one is there) properties then driver and update. select the folder you made for the zip press ok.
If you do not have one installed then go to start-settings-control panel-ADD NEW HARDWARE. select the option where you make the selection then select modem next sreen, select have disk, then select the drive you made the folder, select it and the inf file should show up, then select ok until the driver is loading.
If you need another driver for another OS let me know.