Enter the Final Cut Express 2 package by control-clicking on it and selecting "Show package contents." Inside the /Contents folder, you will find the file info.plist. Open it with Textedit and you will see this:
...
...
<key>AELMinimumRAMSize</key>
<string>384</string>
<key>AELRequiredCPUType</key>
<string>G4</string>
<key>AELMinimumCPUSpeedSingle</key>
<string>350</string>
<key>AELRequiredIOPCIDevice</key>
<string>AGP</string>
...
...
Go to the line <key>AELMinimumCPUSpeedSingle<key> and replace the value 350 in the following line by 0. Save your file and exit TextEdit. FCE should now start up without any problems.

