There are usually two ribbons - a primary and a secondary - and these have two connectors - a master and a slave.
As for a power cable, if you don't have a spare, you can pick up a Y-splitter cable for a pound in a computer fair or £3 in PC World (saves waiting till Saturday).
If all else fails, you can purchase a PCI card which will give you an extra EIDE channel.
What do you have at the moment? HDD and CD-ROM I suppose.