What do i need to water cool?

Don't water cool unless you have a 100% functional need for it. Water cooling is very expensive and is also high maintenance.

Also all in one kits do not cool well compared to an actual custom water cooling system.

For example if you look at the all in ones from Corsair, you will see that they only perform a little bit better than a quality air cooled heatsink (the level of improvement is not enough to warrant the additional cost.

The only time a full on water cooling system warrants the cost is the fact they they may allow you to push an extra 0.2V into your core i7 CPU when overclocking without it going over 100C

with the all in one kits, you generally cant get to a point where you can push an extra .1 to .2 V into the CPU and have it not overheat. (by extra voltage, I mean when you hit the average max overclock voltage of a standard air cooled heatsink)

Also wanted to add, In the past when I have done custom liquid cooling builds for people, it was hard to talk them out of it (their main focus may have been more of the look than the performance)

Generally for the cost of a liquid cooling system you can generally put that money towards a significantly faster CPU or videocard or in these days, a 120GB+ SSD

Also a single radiator that gets attached to a 120mm or 140mm fan is not enough to allow for more voltage over air cooling only. For something like a core i7 or a Phenom II x4 or x6, you need 2 large radiators (generally a 2 120-140mm fan radiator or a 3 120-140mm fan radiator, and trust me they are expensive)

Also avoid all in ones as even with a large radiator they often lack a decent sized reservoir, which not only make it easier to expand the system and prevent bubbles, they also increase the amount of water that needs to be heated, which helps lower temperatures.

All in all, a decent liquid cooling system if you are interested in boosting your max overclock over what you can get with air cooling, then be prepared to spend around $300-$400 on a cooling system

generally those who get liquid cooling for functional reasons such as overclocking and not for the looks will only get it when they already have a top of the line system where they have more money but nothing faster to spend it on so they focus on getting the highest possible sustainable overclocks.

If you are not that type, then put the money into a faster CPU, videocard, or storage