Yep... Air don't cut the mustard with these Tecs.
Keep on modding Witch. The more you play, the more you'll understand.
Remove min 2 watts of heat for every unit chilled and you'll have some awesome temps.
I can tell you that the cooler the hot side loop gets the better. Don't be afraid of trying Ice in a bucket on that loop to get them Peltiers well into negative temps on the chiller side.
Ever need anything with this TEC stuff for suggestions bro, please don't be afraid to ask.
EDIT:
In fact, I have a 130w (chilling power) TEC. All I need is an addy, and I can send it out. I'd like you to experiment with it on the side. Use different voltages and what not.
Not sure if starting a little smaller would help any with a TEC that can actually cool a Cpu by it's self. up to you, I have a PM box here too