Most likely the drivers on the site will be an updated version as to what you have on the CD. If I were you I would download the "NVIDIA nForce4 System Drivers" driver package, (even though the USB drivers aren't specifically named in the list) and either double click the .exe in the folder that downloads or if you feel more confident update the USB drivers in Device Manager pointing Windows to the folder you download from MSI.
Check whats in the folder before doing a driver update as the drivers could be in compressed files and you will have to unzip them before Windows will be able to see them.
edit....looks like we posted at the same time, just read what I have posted here and let me know what you think or what happens after you download the driver package.
edit... LOL did it again....