The standard goop should do the job at stock speeds. I personally use Type 44 on everything, partly because I trust it, and because I bought an 8 oz. tube years ago, super cheap, it's a lifetime supply.
Before installing the gc68, remove the fan, make sure that the crossbar on the clip is located so that the clip hangs evenly off of both sides of the sink, and that the pressure point will be directly on the processor die. Install the sink, then the fan afterward. The clip isn't great, I use two screwdrivers, one to push down, the other to pry it away from the side of the socket. Far from the worst clip I ever installed, some Vantecs have that dubious distinction.
Nexfan markets the same item as the Galaxy Monster, and they've been sold elsewhere under even more labels. Not that they're some killer HSF, they're not, but they provide performance similar to stock on 1600-1800 XP's at a much lower noise level. They won't fit boards that have tall capacitors near the socket unless modified. Some have indicated that the latest batch from SVC doesn't have as good a finish on the base as older ones. I haven't bought any lately, and I'm not sure how much it really matters, anyway....
The $6 pricetag is correct, goes to show ya just how easy it is to overspend on this stuff....