It is not the most efficient or the most convenient way, but until LionRosetta is released it should do. Run the applications on the virtual machine.
These releases will only run on specific models of PPC Apple Macintosh computers. x86 emulators like VirtualBox, VMWare or Virtual PC will not work. Install Snow Leopard on a virtual machine. Having a virtualbox mac OS is the easiest method of using mac as and when you need it. To achieve a dual system configuration use either VirtualBox, VMWare Fusion or Parallels Desktop for Mac. If you use Lion there is also a solution: Use Snow Leopard: It comes with rosetta which is an emulation layer for PPC apps. Your options are to upgrade your Adobe software to an Intel version, trade in your new Mac for a slightly older used Mac (from early 2011 or earlier) and put Snow Leopard on it, or continue to use your old hardware for your Adobe software. Given that you said your iMac is brand new, it presumably came with Lion preinstalled, and is unable to run anything older. Sadly, they removed it in 10.7 Lion and it no longer works.
Qemu can also run some OSX release previews. There was an emulation layer called Rosetta to allow Intel Macs to run PowerPC applications that Apple provided from Mac OS X 10.4 to 10.6. Qemu-system-ppc can run the PowerPC versions of Mac OS 9.0 to 9.2 and OSX 10.0 to 10.5.
