You would be correct... wait for the mobo. The p5wd2-e has a different chipset to the MSI p7n SLI-Platinum , and you will have to reset the RAID-0 again anyway when the new board comes in.
However, if you really need to you can format the drives now then setup the RAID-0 when the new board comes. But the only reason for formatting would be to test the drives a bit more to make sure they are still stable. which im assuming they already have been for some time