Pamela,
I've heard that some people had problems with 10.0 and 10.1. I have had no problems, I started with 10.2.6 and upgraded to 10.2.8 shortly after. I gave our old G3 333mghz Imac (OS9) to our neighbors' daughter, I was a little concerned about what might be left on the hardrive, so I wiped the harddrive and installed an early version of OSX. When we had the Imac it crashed or froze at least every other day. The neighbors report that it is very stable now.
I haven't upgraded to 10.3, but plan to upgrade to 10.4 when it's released. I don't want to upgrade all the time, but I don't want to get left behind either. My current plan is to upgrade to everyother new version.However, I do plan to keep on top of all Adobe Photoshop upgrades. If that involves upgrading my OS, so be it.
Jeff.