No need, it'll be a closed loop cooler for the CPU. Never need to open it and change anythingHmm wouldnt you want to get some anti corrosive/ electronics safe water for your cooling system?
I've never heard of a store that has a payment plan but I usually order computer parts from NCIX or New egg. I also ordered an ibuypowerpc and it was so crappy I ended up building my own. The power supply they give you is a no name brand.