A few things though... as others have said
-you'll get fantastic results if you invest in a *real* brand waterblock, even the cheapest brand CPU waterblock (like a Phobya UC2) will drastically outperform the contraption you have there;
-you need bigger bore pipe, like 1/2 " (12mm) , the current 1.4" (6mm) is waaay to restrictive for any length
-with bigger bore pipe, you may be able to get away with the pump you have, but even so... consider getting a decent D5 pump in the long run
Now, if you really want, you could go to the plumbing/heating section of the local hardware store and look at the stuff needed for underfloor heating, including a Grundfoss HVAC pump
You could make it soo large that you could hook up a bank of computers to it
On more thing thou.. you know what happens to copper over time when encased in concrete/cement? ..
Ask a plumber.. if he says "nothing at all", then NEVER have that plumber do anything for you.
But i like what your doing, its a good starting point to get serious