That should be plenty of free memory! Is there some reason that you used the .cab file rather than installing using FTSetup.exe? Usually it's only necessary to use the .cab file when the game won't install from your PC. I prefer using the PC setup, since it makes sure that everything is installed in the right place. You might want to try that to see if it makes a difference for you.

If you're still having trouble, please post back here.