active partition

how can i make a disk with ntfs or fat32 partition active? i have xcopied from an ntfs disk to another and when i switch the drives the pc will not boot up…i am sure cause no parttion active on the c drive..i tried using fdisk off a win98 boot disk, but that screwed up my boot with hardware drive configuration errors….how can i turn a drive in active that is formatted in ntfs and one that is formatted in fat32?
thanks