I have the 2.2 1MB Cache but I have it overclocked to 2.6. The Cache size doesn't matter as much on 64s, so generally it's better to get the higher speed; I didn't do much research before buying either (don't get the same ram as me).
I have mine at 2.6 on air without any problems. I've never messed with water cooling, thought about it, but every time I do I say to myself "why am I putting water inside my computer." Just doesn't seem smart to me, GL though, talk to scottchen.
And the Claws does clock for clock with newcastles, if not better. You'd think that the smaller die size on the newcastles would generate less heat and have chance to go higher, but read somewhere that newcastles are just defective clawhammers.