THe RAM you linked to is not compatible with your board. You are currently running DDR400 (PC3200) which is more expensive than DDR2 now. If you are not overclocking then I would recommend Corsair Value Select DDR400. To maintain dual channel mode you need to have an even number of RAM modules (2 or 4 sticks).
Look on the opening page of CPU-Z and see if your processor is Rev E. If so, you should be able to run 4 sticks of RAM at 400mhz. If not it will default to 333mhz with 4 modules installed.
Of course, anytime you mix two different kinds of RAM you run the risk of compatibilty issues. The new RAM may not get along with the old RAM.
