That motherboard is Socket A, and northbridge on it is AMD-761 so that any Socket A cooler can go on your processor.
As for northbridge heatsink ... as I can see, it is glued onto northbridge, so you will have to be very carefull if you will
try to remove it .... I do it with wide screwdriver ... place it under the heatsink and twist easily ... until it pops off ... but
you have to be very carefull not to damage the PCB ... couse that could kill your MoBo ... When you remove it, you
can place Zalman onto it with Zalmans glue ... couse you cannot screw it onto the mobo ....
Do you have ventilator on that heatsink ? I can see on the web that there are those MoBos with and without the vent,
so if you don`t have it, there is the easiest solution .... place a vent onto it .... you dont need anything more than that.