The 2 main key topicquestions for my essay are how liquid cooling improves a computer's overclocking abilities and how this increased overclock affects the performance of the computer?"
Sounds good, but I'd add onto it a little:
0: Give a brief explanation of what OCing is.
1: How does said OC affect the PC's performance?
2: Explain how a water cooling loop works.
3: How does water cooling impact OCing?
4: How does said increase in performance compare to the amount of money put into the cooling system? How much would it have cost in upgrades to get the same performance increase, if any?
Given that I don't have the actual circumstances or guidelines as to how you need to write this essay, I can't really get very specific into anything. Just a few quick ideas...
As to which water cooling kit to get. Not a clue. I've always been an air cooling guy myself, so I'm of no help whatsoever in picking out parts.