Artic Silver on an Winchester

My parts are on the way for my new system, and when I get all my work out the way in two weeks I'll get to build the machine I never though I could afford! Anyway, the question I have is, I was planning to put an XP-120 heatsink on my CPU (64bit Winchester) and using some arctic silver for a good thermal conducter. When I did this with my current XP2500+ Barton I only had to put the arctic silver on a small area... looking at the new chip I have the surface area on top of the chip is pretty much the whole size of the chip. Now in danger of sounding stupid, do I have to cover the whole surface area that makes contact with the heatsink? Any other advice on the method?

Cheers

-Leonard Burton

http://www.arcticsilver.com/images/p4_as_dab2a.jpg
http://www.arcticsilver.com/arctic_s...structions.htm