You do get readymade water cooling kits. Kits from Swiftech are very decent.Although buying seperate parts and configuring your own setup is always going to work out better but then might turn out a bit expensive too.
You can look at
www.sidewindercomputers.com
Instead of going for a water cooling setup, you could also think of buying the Thermalright Ultra 120 Extreme cooler and use a high cfm fan with it and it will give cooling equivalent to a basic water cooling system and you can also save some money.
Or else, you can sell your CPU and buy a new CPU based on the Core architecture as there are lot of options and are cheap and much much faster compared to Pentium D series.
