None of the replies and explanations mentioned virtual memory, an OS X default and an OS 9 option, and how it is effected by partitioning. I just checked my 30 Gig drive and it has a partition of 2.6 Gigs, or 10%. I would imagine, but don't know for sure, that if you create partitions that are quickly filled up, you will run into virtual memory problems which may cause slower performance or other problems. There are also scratch files that may run into disk space problems. Video and graphic programs need lots of scratch space or they run slowly, maybe crash. I have yet to read anyone discuss this possibility. Another problem is stability of the disk. I have had partitioned drives fail but not after I erased the drive and set it to only one partition. I don't know whether that experience is common or an anomaly. The idea of being able to reinstall OS X from OS 9 partition seems a bit odd since the OS X installer does not run in OS 9 but reboots from the CD whether you are in X or 9. Am I wrong? Also a partition may be more likely to become corrupted than the hard drive and I have experienced several partition failures but no hd failures other than my original 20 Meg drive on an SE just after the 90 day warranty expired. I don't have 9 installed and run only OS X. So, I avoid the issue of separate partitions for the two OSs. The only reason I would consider partitioning is to download video but now that Apple has sorted out the firewire problems to some degree, I can download to an external drive. I backup my internal to an external LaCie Pocket drive. If I need to, I can boot from that and then backup to the internal. Unless you are really forced to run OS 9, the best move may be to not install it. And, reading of the problems people are having with fonts, this might prevent a few. Installing it on an external drive for emergency use only might be a good choice. Having separate drives for applications and documents is a much better idea than having separate partitions but, of course, not that practical with a Powerbook. Maybe some day Apple will have an epiphany and replace the seldom used cd/dvd drive with another hard drive or at least give us the option to do so. External burners are faster, way faster. Look how small the drive is in the iPod... Google 'Drive Failure' and then add your drive manufacturer such as 'IBM Drive Failure' or 'Maxtor drive failure' or "Macintosh drive failure". --- Using a Merlin C201 Sprint Wireless Modem Card in a Titanium Powerbook G4 and getting 123.1 kilobits per second downloads...almost 4X faster than dialup. The salesman said it wouldn't work in a Mac... JackRodgers at earthlink.net http://www.JackRodgers.com http://www.LobateLacScale.com