It also reveals that Gateway or those other makers are your source of support and not USR.
Charts!
http://www.usr.com/products/business/compare-business.asp
http://www.usr.com/products/home/compare-home.asp
Aha! Not a single Vista item in sight.
-> http://www.google.com/search?hl=en&q=vista+voice+modem&btnG=Google+Search finds the Hiro. Maybe others.
Sorry but as no one does dialup here I can't offer much else.
Bob

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic