Are you talking about drivers for the computer as whole or just drivers for the usb program cable?
If you need drivers for the computer, then go to their web site and lok for them, if you need driver for the program cable, the google proflic usb drivers and down load PL2303.
This driver works with just about every usb cable that I use (over 20 differant cables) and then you should be good to go.
Also, make sure that you are using the correct com port. plug the cable into the port, open computer properties, hardware, device manager, com ports and see what port is id'ed.
After you have done that, open the program and check what port is maked, should be the same.