Yeah arctic silver five is way to go, even better is a big tube of it, then put it in an airtight baggie for years of use.
I prefer to rip off all my stock heatsinks, use isopropyl alcohol with a qtip (usp from a pharmacy is fine for me), and then AS5 them all and put them back on. Trully works wonders, even lowering case temps by some way im not sure how?!
www.coolerguys.com has some stuff for it, they are a nice bunch of people there.
The difference in stock vs as5 is 3-5 degrees sometimes, which is incredible for sticky goo