I installed canon DPP after a few people said it was good but it wont preview images from the 5D2 WTF? so i gave up
You installed an older version of DPP. Like every other RAW converter out there, if the camera that creates the .CR2 file is newer than the software, the software won't read the file. When a brand new camera comes out, only
DPP can read the RAW files. Others are updated in days/weeks/months as the software vendor incorporates the new code. In some cases for paid software (Adobe, DxO), if an upgrade version of the software comes out (e.g. CS4 to CS5), you must buy the upgrade to open RAW files from cameras released after the upgrade came out. In other cases, e.g. Aperture, Apple releases updates that support new cameras, for free.
From what I've seen, Adobe and Apple are first out with support for new .CR2 files, DxO lags (because of the more extensive testing they do for the lens correction modules). For example, when I got my S100, only DPP could read the RAW files. Adobe and Apple released updates which included the S100 in early November (although Adobe's is an RC, i.e. late beta). DxO's module for the S100 is due out in January, 2012.