Tom's said not to use any at all because the heatsink and processor were supposedly lapped so well that they were perfect and didn't need paste.
I think it's best to go with arctic silver 3 still. On their web site, they have clear instructions which describes that part of the job of arctic silver 3 is also to fill in microscopic air gaps in between the CPU core and the heatsink or waterblock. Also, judging by the fairly high CPU temperatures they achieved in the review when not using AS 3 I would concur that using AS 3 would help.
1° of separation between my monopoly and yours. That's business with .NET