I had a 2 gig HD and was never able to egt it installed. I went to a 9 gig HD as thats what I had available and, voila! it installed. Installation took about 10 tries until I switched to the bigger drive. I have not found YDL to be a huge revitalizer of my PM 8500. It is fun to play with but does not seem anywhere as brisk as MacOS 8.6.