Apparently, there are others in a similar boat. I installed Final Cut Express ver 4.0.1 on my new iMac running OSX ver 10.8.3 and it works great for "not supported". I don't recall specially installing Rosetta (normally used when dealing with PPC CPU based apps to Intel CPU). Have you tried to load the older version of FCP and got an error message? I remember reading that the older Final Cut versions were "not supported", but after reading through some of the apple.com support areas, it seems nothing exactly breaks, rather, the older app versions don't take *efficient* advantage of the multi-core processing that FCP X does. But FCE 4 installed just fine from the original disc (glad I did not lose the serial #).