What kind of IDE cable do I need?

Ok, here's the problem that I have. I have a homebuilt system with a micro-atx mobo. However, the case that I'm using is full atx form factor. I'm currently using an IDE ATA 100 hard drive as my primary storage device. I also need to hook up an IDE dvd drive. The mobo I have only lets you connect up to two IDE devices. The IDE devices would have to be connected with the same IDE cable, since there is only one slot. The 19" cable that came in the box is not long enough for to connect both a dvd drive and hard drive. How do I know which IDE cable is right for my PC? Obviously, I know that a new cable would have to be longer. But I also need to make sure that the space between the master and slave connectors is long enough. Can someone please lend me a hand here?