If you look at http://www.ifixit.com/Guide/search/titanium+powerbook. Find you particular model. You can disassemble the PB yourself. It's not hard with some simple tools. Then you compare your disk drives. They should -- I believe -- be ATA/IDE drives. I'm not sure about that. Take out the old one and save it. You'll need a cheap Firewire enclosure for that drive. MacSales.com has them. When you get the enclosure, install the old drive there. You can install the PC drive in the TiBook if the interface is the same. Then you connect your new external HD (your old disk), and boot from this new external drive. You must reformat the PC disk as a mac volume. Then you must install your OS on it. Finally, you run Setup Assistant or Migration Assistant to copy everything properly from the old drive to the new one. You should then be able to boot from the internal drive, Check the permissions, and perform all software updates. Recheck permissions. One final note, you are going to a lot of trouble. Is your new drive big enough (capacity) to be worth it? David On May 20, 2009, at 11:50 PM, Arne Hulstein wrote: > Can I put a harddisk that used to live in a pc laptop in my tibook > to replace its dead harddisk? And how do I get MacOS 10.4 back on it > as it came installed with it and I have no cd's around here... Are > there tibook downloads? > > Arne > _______________________________________________ > Titanium mailing list > Titanium at listserver.themacintoshguy.com > http://listserver.themacintoshguy.com/mailman/listinfo/titanium