Hard Drive will not boot.

I have 2 hard drives; an 8gig on IDE and a 14gig on a Promise ultra 66 card. I want to remove the 8 gig drive to sell to someone. The drive I want has windows already on it and it totally usable but when I try to boot from it, I get a message that says “not a system disk.” I tried going into Fdisk and chaging that drive to active, but I get a message that says “only drive one can be made active” There really isnt much on the 8gig drive and I really want to get rid of it. If anyone has any ideasplease let me know.