With my el sh*tty Nokia 6233 cam, No thank you.
You're in the same dilemma as I was prior to adding my after market cooler. Those temps will keep rising unless you either kill the card & RMA it or open up the heatsink & clean the dust settled on it. Blowing air around it won't help at all. Trust me, I have been through this cat-mouse game. Try claiming an RMA for excess heating. I don't know how MSI's policy works but my GeCube has a 1:1 replacement policy. If it's the same with yours then you'll get the replacement quite fast. The chances of getting a dual slot cooler would only be if they don't have the same model (single slot cooler) in stock with them.
@redmanc: Is your card recently purchased? The idle temps are really good. No need to tweak anything with the fan speed. If you do want to try it out then set it to 45-55% which should be more than enough.