We've recently acquired the SB5100 with optus, but

We've recently acquired the SB5100 with optus, but we've gotten a new laptop n it wont install properly n fail the connection test at the end. My bf had this problem too with the same modem he had to call up n they charged him for 5 seconds of work n their modem worked again. If its so quick n simple why cant i figure it out? were using the USB connection coz we dont have ethernet cable. AWe have disconnected the old comp n no longer using it. Why wont it owrk.