replacing your old fan with the new one is pointless you are almost replacing it with an identical fan, you should look for high cfm (cubic feet per meter) and low dba (decibels, noise) its to get the right balance of sound/performance ratio to suit your needs http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Expensive but moves a lot of air quietly
The 120mm actually pushes more air. If you are having heating issues you should look at the airflow direction, obstructions, etc. A new case, or heatsink may be in order instead.
haha...Actually my pc is a mess inside. I have to work on my wire management. But i think my pc is pretty cool for the time being. I recently got filters which are obstructing flow from side(x1) and top(x1) and was considering to get a more powerful fan to get some sort of air flow going from side(intake) and top(exhaust). BTW the case is a Cooler master HAF 912, it has more room than i thought.