Works OK in a 32bit system so assume you are trying to install in a 64bit system.
64 bit Vista drivers will do the job in W7
BT Voyager 1055 USB Wireless Adapter requires the two driver files 'rndismpx.sys' and 'usb8023x.sys'.
Downloaded the latest Vista driver from the BT website HERE and then before running the install program right click on the install file, selected Properties,
Click on the compatibility tab and select run this program as Windows Vista SP2.