That's some very nice RAM, but honestly, with your unlocked multiplier, you don't actually need it. You've already got 2 GB of DDR2-667, and a 333 Mhz FSB is really fast enough for a dual-core processor. I think you should just buy that Ballistix PC8500, and send it to me, because my Ballistix PC8000 is feeling lonely.🙂
Anyway, in a nutshell, will it make your system slightly faster? Yes. $120 Canadian worth? Not in my opinion. If you buy that RAM, you most likely won't feel any difference at all, you'll only see it in some benchmarks. Have you considered buying two more identical sticks of what you have right now?