If the bios says it is 12gig then you must have done something wrong in fdisk.
If you boot up and in the options menu choose 'dos prompt' you can type dir there and see what size dos is reporting. If it says 12gig then you have a windows problem, if it says 2gig then it is something you did when selecting partition sizes. Are you sure in fdisk you deleted the old partition first? or did you create a new one with unused space and make it active?