I doubt seriously if there was ever a specific driver written for Windows 2003 Server since you don't commonly find scanners attached to Servers. That's a hardware device that would be more commonly found on a workstation.
Mustek Bearpaw 1200CU Plus II USB Driver for Window XP/2000
Version: 18.104.22.168 and 22.214.171.124
File name: 1_MustekBearPaw12.zip
File size: 1,133 bytes
Hardware ID string: USB\VID_055f&PID_021c and USB\VID_055F&PID_021B
I also find some drivers POSTED HERE
in case you wish to try any of them.
And btw, scanners do not have PCI/ISA interface. This scanner has a USB interface.