The original 2003 rear shock didn't have any damping adjustment only spring preload, so yes the 2009 shock will fit and it will be a improvement over what you have now, it also has a damping adjuster screw so you can set the suspension more to how you like it.
Make sure that the 2009 Olle shock is in good condition, slide the bump stop down so you can check the shaft for any wear or pitting, make sure the seal isn't leaking, check both bearings as these can be expensive to replace and check around the top and bottom of the shock for any damage.
Your other option is to get your original shock serviced, the oil will be 8 years old now so it's going to be well past it's best, we can get this done, if this is of interest to you email me