Chiller question. 
I would get the biggest chiller that I have the $$$$ for. Before dumping money into a chiller, make certain you really need one.
Here is a good starting point to determine the size of chiller, http://www.aquarium-chiller.chaninternet.com/
Don't forget to check CraigsList for some good deals on a used chiller.
135g Main Tank/ 125g Frag tank with 55g sump.