I have the same pump as you but I have the older storm water block.
The pump is good, good head pressure and quiet. The pump goes well with storm because the jets inside need that pressure... If you take apart your water block you will know what I mean.
I generally have a CPU temp of 40-45 under load. (I have OCed my Dual core 3.6 to 4.8 with 1.5 vots).
To give you an idea how good the wc setup is: I used to use a zalman 7700CU I had my CPU at about 4.2 and it was about 70 deg under load. I couldnt push the CPU more because I was getting abit worried about the heat.
So yes the water cooling helps quite a lot.....
Make sure you get those 1/2 inch ID Tygon tubes...
I use a Black Ice Extreme III rad + 6 Panflow fans...
Dont use tap water try and get double distilled water.