I have 10.5.X on my 1.25Ghz eMac. When I first got it I put Leopard on it, and then bumped back to 10.4 because the difference was significant enough for me warrant the downgrade. Then I upgraded it to 1GB of Ram an reinstalled Leopard. It worked well enough for my daughter just going to Disney channel and ePets. I didn't notice it being overly slow for her. Significantly better than the G4 800 she had, but 10.4 was surely smoother. Then I found out you could actually put 2GB of Ram in the eMac. So I installed that and replaced the hard drive w/ a 7200 RPM drive and now it's quite nice. Not for the faint of heart, but fun for me. I can see her using this already nearly 5 year old machine for another 2 years unless it were to fail.