I was asking myself this question this afternoon. I ended up going with the 3800+ X2, for a few personal reasons.
1. I have an Opteron 144 right now with the 9x multiplier, and it's been kind of a pain overclocking with the 9 multiplier with my value ram. I'm hoping the 10x multiplier of the 3800+ will make things a little easier.
2. I heard that the 3800+ runs a little cooler, I guess due to the lower amount of cache.
3. I already have an xp-90, but if I didn't have one of those, I would have gotten the 165 with the massive stock HSF.
4. I put the $34 I saved towards an NV Silencer for my 6800GS.
We'll see how it goes, should be here Wednesday, then there will be an Opteron 144 on the FS/FT forum shortly thereafter
