I think that you're looking for some extreme cooling definietly.
Phase change systems are very nice, but kinda pricy. It may be problematic to get one in reasonable price, unless you have some time and knowledge for DIY rig.
Water - you'll get performance boost over your current cooling if you get good parts, but don't expect huge temp drop unless...
Water cooling can be extreme too, if it's running with water chiller (which I personally consider dumb) or when you run it as bong. With bong cooling water temp drops below ambient - the more water evaporates, the lower temp. This way on nicely OCed system, you can get CPU temp close to ambient. Such solution is a bit cheaper than phase change, but as you haven't got WC already, I'd recommend phase change if only you really need such performance and can afford it. On the other hand, bong system can be easily sued for cooling any parts for which you find water blocks - north bridge, GPU or others.
phase change
+++ extreme performance
+ can easily run 24/7 without looking at
- expensive
- chills only CPU (if it's DIY, it can chill everything)
- uses more power than water cooling
- risk of condensation when mounted incorrectly
bong (we can forget normal WC I think)
+ very good performance
+ can chill everything
+ a little cheaper than phase change
+ uses less energy than phase change
- water level needs to be checked
- and water needs to be added from time to time\
- won't freeze your CPU
- risk of water when mounted incorrectly
- depending on layout, can be noisy
I'm planning to convert with my pal his WC rig to silent bong soon. We'll see how it's going to perform, but I dobut taht you want to wait that much. Maybe check extreme cooling subforum?