Go onto ebay and purchase a pci sata card for about £3 to £4 for a card that will give you 2 external e-sata ports and 2 internal sata ports. Good luck this is the best of both worlds as most large 1,2,3,4tb drives are external e-sata now and are becoming more and more popular.
I agree with jesops - a cheap SATA adapter card is the best way to go. It's getting hard to find IDE drives these days, and even if you do find one to plug into your existing motherboard you'll likely be out of luck with the next generation of motherboards since IDE connectors are rapidly going the way of the dinosaurs. So a SATA drive + SATA adapter card is a better future-proof solution.