The Thermaltake Blue Orb appears to be your best bet. Depending on your card it can be easy as unclipping the old fan and clipping on a new one.
For other, you must first pry off the old fan since it is glued on. In my experience just shove 2 credit cards between the fan and heat sink, then stick a screwdriver in between and pry off. There are two schools of thought on when to do it. Some say you should run Q3 for a few minutes for the glue to get soft. Others say put it in the fridge to make the glue brittle. I usually just do it right out of the system.
After the old HS/fan is unstuck, you can either apply with thermal tape (okay thermal properties but removable) or use Arctic Silver Thermal Epoxy (superior thermal properties but nearly impossible to remove).
Windogg