The 9550 uses a considerably slower core over a 9600(pro) - 250Mhz over 400Mhz - but some cards had the ability to be software/hardware modified to beome a 9600Pro in the PC world.  I'd google the exact card to see if it has the ability to be BIOS modified to a 9600.  Also remember that a 9600XT is a different card and you can't flash to this.  Looking at the available ROMs, there isn't much of a choice so I suspect you might have difficulty.

JB