the amount of heat being dumped into your hall will remain the same, no matter what cooler youre using. perhaps the water will absorb some of the heat and reduce the total heat output initially

as for noise, well:
1. your AMD stock cooler needs replacement. find something that is quiter.

2. use nvidia's ntune to control the speed of your 7600GT's fan speed at 2D. at 25% it makes no noise whatsoever. this solution is free!

3.casing fans and restriction: if there are fan filters and lots of restrictive things in front of the fan, remove them! dust filters restrict ALOT of airflow and the fans suffocate and create tons of noise. if you can do without dust filters, remove them.

good luck