Yes, I believe it runs under Rosetta emulation. Other posts have reported no problems. However, some people have written here that CS2 runs extremely well in OS10.4.11 ( Tiger ). Personally, I believe that the performance matrix involves three factors: 1.) CPU; 2.) OS; and 3.) CS. If you're running a G5 ( PowerPC ), according to Apple, your days ( as well as mine, I'm using a G4 ) are numbered. Apple recently announced no more "Rosetta". You may want to reconsider upgrading until it is necessary ( i.e., PowerPC dies ). Sure, you can upgrade for your own personal reasons, but 10.5.whatever will be the last upgrade that will run CS2.