IDE Hard drive upgrade

[CIS121]

The hard drive's gone in one of my PCs and I'm looking to replace it. It's a IDE 40GBdrive from about 5 years ago. Can I replace it with any IDE hard drive or are there likely to be compatibility issues?

I've been looking at drives with ATA100 and ATA133 speeds, but will these work with all IDE connections or do yuo need a more modenr motherboard to work with these later protocols?

[CIS121]

Thansk folks. I was just worried that a 133 drive might not work if it came with a 100 one.

Thanks!