winmodems are notoriously hard to get working,
Because Lazy hardware vendors are too slack to support linux.
Next time you buy a computer, show your support for linux and
buy one which supports linux
Of course, that doesn't help you right now.
The only drivers for connexant winmodems I know of are the Linuxant drivers, which you can get here :
Unfortunately, to get full speed out of them, you need to buy the driver.
(Which sucks, but it was the only way they could get around Connexant's NDA and still have a usable driver)