The drivers for this device are not installed. (Code 28)

I'm trying to attach a McLelland USB Preamp to my desktop PC. The desktop
PC is running fully patched Windows XP Pro SP2. This device is supposed to
come up as "USB Sound Device" which it does in Add Hardware Wizard. It is
also supposed to use the defauilt USB drivers included with Windows, but the
Add Hardware Wizard can't find drivers for it.

My laptop Windows XP Media Center finds the preamp as a USB Audio Device and
it works fine there.