CS2 will never be able to process RAW files from the 5D2. Adobe won't even update CS3 to handle 5D2's RAW so like frankchn said, only CS4 can do it. There are many other software that can handle 5D2's RAW. CS4 is expensive but the student edition is very cheap (if you are a student), Aperture 2 is pretty affordable too. If you really want free, Canon includes DPP for free to process your RAW into JPG then you can edit with your CS2.