With all the posting of problems in upgrading to 10.4, I thought I'd share a positive experience with everyone. I have a 4th gen. 15" powerbook, purchased a couple of months ago. I upgraded to 10.4 recently, and things went without a hitch. No conflicts, everything works as it did before, including my wireless and bluetooth connections. Speed improvements in Safari and overall performance are obvious. I was a little bit afraid of upgrading, but now am very glad that I did. The speed increase alone is worth the upgrade.