Same here. I mean, nothing wrong with it, but I just don't understand why it seems to be so important to you. Tracking down original CDs on eBay or the like "just to have them" in your collection is cool, but why is it so important to have disc images of basically useless software? (not that I don't have some Gigabytes of useless software lying around myself, get me right)
But on Macs in my collection, I usually istall the original OS whenever I have the discs or it's easy to find, but when it's not I'll just go with the most stable version, like 7.1, 7.5.5, 7.6.1, 8.1, 8.6, etc…