You need to edit the Arduino UNO.inf file in the Arduino drivers folder.
Find the following section at the end of the .INF and change DESCRIPTION="Communications Port" to something like DESCRIPTION="Arduino UNO"
You will need to uninstall the driver for you Arduino first, then re-install with this updated INF.
;------------------------------------------------------------------------------
; String Definitions
;------------------------------------------------------------------------------
;Modify these strings to customize your device
;------------------------------------------------------------------------------
[Strings]
MFGFILENAME="CDC_vista"
DRIVERFILENAME ="usbser"
MFGNAME="http://www.arduino.cc"
INSTDISK="Arduino UNO Driver Installer"
DESCRIPTION="Communications Port"
SERVICE="USB RS-232 Emulation Driver"