Does anyone know if Cubase VST 5 will run on a new Imac in Classic emulation mode? The new Imacs won't boot up in OS 9.

No, real-time applications like Cubase won't work in classic-mode. But Cubase is available for OS X.

Go to their website. www.steinberg.net. I don't see it listed in their product line. I doubt that it can be used with OSX or the classic environment. I have the new G4 which cannot boot in OS9 either. You're going to have to upgrade to something else, preferably something that is native to OSX. Always check out the system requirements.
gfclef

Be aware that SX is a totally new app. With a whole new set of issues.
SX2 is due next month.

I suggest you check out the Cubase.net forums. but in general they are not happy campers over there.

I choose to look elsewhere for my OSX audio needs, after beining on Cubase since version 3.
Check out the forum, the issues are well documented.