Yellow Dog in early 2000s, and I think I switched to Debian PPC not long after. My memory of back then is quite hazy. A way while after that I had an Eee PC which I think I put Ubuntu on initially (the desktop was dog slow) and then changed over to LMDE. Have a feeling I had something else on it before Ubuntu… may have been the default Eee distribution, which I forget the name of (think it began with an X).
There’s also Free95