You might need to remove it via the device manager (if it is there); shut down the machine, physically remove the modem, restart, shutdown, install the modem to a different PCI slot, and upon restart it should be detected.
I hope that is not too long winded... if you need drivers, have a look at driversguide.com
The question I asked is important. There are at least 2 versions of the SupraExpress 56i V Pro, with different chipsets. You have to use the correct driver for the chipset. The earlier version was originally supplied with a defective driver on the disk, and should be installed with the later driver from the web site.