I plugged in a USB speaker dongle and though the speakers connected to it work, I cannot control the volume from within Windows, I must manually adjust the vol on the speaker.

I have made adjustments to all the OS-based speaker settings, etc.

My USB speakers dongle: PD552 from COMODOW

I tried installing their driver, but it would not install. Presently, the dongle is using Windows built-in USB Audio driver.

I have Vista Pro OS.

Any guidance would be appreciated.

perhaps the PD552 USB speaker dongle drivers don't allow you to control the volume with Windows Vista, which is why you have to adjust the volume on the actual speakers themselves rather than using the software volume controls in Vista.

check the PD552 manual (if Comodow supplied one either on paper or on the CD) and see where or how to adjust the volume controls.