Hmmm... strange. I have a similiar setup of the same board, and a Leadtek 5900u, intel 3.2gz but Corsair TwinX memory. I am running at 220x16, so 3.52ghz and my last 3Dmark03 score was 6972 so very respectable.
I have read off of the MSI boards that there may be some issues with that memory.. (I think) Definitely hit http://forum.msi.com.tw/index.php?sid=
and look for some help. The folks there have been great for me.