OK. Are you sure your motherboard does not have an IDE connection? Every motherboard I have owned always had at least one IDE connector. Even my SFF desktop has one for the CDROM.
EDIT: The adapter you want is on Amazon for under $20. No need to buy a PCI card, the right adapter fits on the back of the IDE drive and uses the same power connector. Never use one, but Amazon is careful about selling junk. It is always good junk.
Be sure and select if you want to an IDE drive or a SATA drive. The have both kinds of adapters.