This is a link to your cooler.
http://www.speezeusa.com/5f353b1l3.asp
If you look at the bottom of the page, the last item is "Thermal type".
And it says "White greesse pre-applied".
I am not familiar with this.
I have seen thermal pad being on many coolers.
If I were you, I would get a bottle of 90% alcohol from pharmacy and clean the bottom of the heatsink from the greese (after peeling off the cover).
I would order Arctic Silver 5 or just get it from CompUsa. Apply very small amount as specified on the Arctic Silver instructions on their web site.
If you are not into overclocking, you can use the heatsink with the stock thermal paste. But, I am not familiar with paste having been "pre-applied". I don't know how they can control the paste from being wiped off while handling. So, that is why I recommend Arctic Silver, which is the best thermal compound.