Yeah, 8 years ago 1TB was not even a thought- you need to get something in the neighborhood of 250GB. Your only other option is to get a PCI sata card and use that to connect the 1TB drive. But then you're putting more money into the old machine.
I say, if it has IDE it's a dinosaur and should be left to the museum. Build a new one with a relatively new motherboard and you'll have no issues.