This is a generic driver for modems that are using the Conexant chipset. Diamond Multimedia's SupraMax 56K USB V.90 is using this chipset. This means, this driver will work on this modem and has been proven as I have tried it on my Windows XP OS. Unzip the file and read the "Readme" file and just follow the instructions for installation. Since, this driver is specifically for V.92, you will need to add an INIT STRING to force the driver to work on V.90 protocol.
First, go to Control Panel... Phone & Modem Option... click Modems... Properties... then, Advance... here, you'll see "Extra Settings".. you need to type-in the string in All Caps
Try it out!! Good Luck!!