I got this from
http://blogs.adobe.com/jnack/2007/10/adobe_apps_on_l.html
straight from the horses mouth....I think it sucks myself...these programs are not cheap and it really isn't fair for Adobe to expect us to go out and spend the money again to get CS3
you are under no obligation to update your system software. Running Tiger on your existing mac with Photoshop 7 is just fine. There is precious little in CS3, or in Leopard, that the vast majority of my customers will use or need in their daily work life.
For that matter, there is a whole lot of functionality left in Photoshop 6 on OS 9. -- except for where the Internet has taken browsers, Classic is still a completely functional workspace.
Most people upgrade just because... no science behind it, little thought. Ooooh, it's shiny. I have to have it. Don't laugh, we have all done that here. And it's not needed.
I run a server farm for several hundred hosted clients. I run a consultancy offering contract sysadmin support to hundreds more. Maybe 30% have moved on fully to Intel/Leopard. Another 40% have some mixed machines, and the remaining 29% are running Panther/Tiger on PPC. <1% remains running OS 9, but he's a curmudgeon.
Guess what? Curmudgeon is a well-known author and cartoonist. And OS 9/Word 98/Canvas 8 is what he loves. His G3/233 does just fine for him, along with a zip100 on a SCSI chain. Remember those?
I run a PowerBook AL 867 with both Tiger/Classic and Leopard partitions. I haven't bought CS3. Photoshop 7 in Tiger does everything I need for web work, as does GraphicConverter 6 in Leopard.
We cannot fault Adobe for pushing the 'latest' and abandoning code that was written for PowerPC and not easily converted to Intel -- 5 years ago. They got blindsided by Jobs and the Intel migration. They (Adobe) have shown that they still can't write a standard application package for the Mac in OS X. CS3 is an abortion of a product. CS4 isn't any different from what I read. But they should be spending their resources on CS4 and not 7 or CS -- code that will never be up to Leopard's standards.
I'd tell you right now -- don't move to Leopard unless you have to. Don't upgrade your Mac unless there is a compelling technical need. Shiny doesn't cut it. Your tool today will continue to crank out your creative, inventive, or boring work just fine, and no better with the newer flashier versions. Unless the speed difference between CS3/Leopard and 7/Tiger is too great to ignore and it saves you hours/week. In that case, you've just told me that the product upgrades will pay for themselves monetarily in a few months -- and save you money/time in the future. In that case, they pay for themselves, so why whine?