You mean one you've created yourself, or the drivers disc which came with the soundcard?
Drivers discs supplied with products almost
always have outdated drivers on them.
Whilst they normally allow you to at least get the product working initially... you're always best to visit the manufacturer's website, and grab the latest drivers.
You'll find the ('Audio') drivers for the Asus Commando
here.
Although I suspect they're probably the same drivers... select the one appropriate to whatever version of Vista you're running (32bit/64bit)