I got Vista drivers from the Lenovo site for my Thinkpad Z60t and they work. Of course, it doesn't do me any good because I don't have a Verizon account. My Alltel USB card doesn't work with Windows 7 and I don't believe it will anytime soon.
The Sierra card in my Z60t Thinkpad is built in. I went to a specific driver download page for my laptop and downloaded the drivers. Not sure if they would be right for your system. I just suggested the Lenovo site as a possible place to locate drivers for your aircard.