which waterblock....Z4 or Koolance?

I'm gonna go into watercooling while not oveclocking yet.
I am cheap so I have the option of the:
Z4
or the Koolance Liquid Cooler: CPU

I am hoping to stick to one of these, unless they both get killed by your responses, and an alternative is suggested. I live in ireland, so I have to buy them from England, who sometimes have to order them from USA and such, so cost is a big factor. The two WB's above are fairly cheap.

I really need to find my WB soon, as I want to start building the system around it.
Let me know what you think of them.
All suggestions will be really appreciated.

there is no comparison in my mind. the Z4 is supierer in every way!
except cost.
1-it performs better.
2-the internal design is a big plus.
3-its solid. all metal has better heat dissapation back into the water.
4-if you go with 1/2"od Z4 the inside diamiter is alot larger. therefor u get better water flow.
i use the Z4 and it 100% gets my recomendation!