It is my understanding that all Intel-based Macs are 64-bit capable, but earlier ones (including my 2007 2.4 Ghz Santa Rosa 17") have artificial limitation. I've successfully updated the script to x86_64, and under System Profiler I still get "64-bit kernel and extensions: No" From what I can tell it's the Kernel version Darwin 10.6.2 that needs to be upgraded/hacked, but have seen no info on how to do this. Recently upgraded to 4 GB RAM as well as an 120 GB SSD. This computer is 4 years old but it is still fast. Boots in 10 secs flat. The only thing is I'm running CS5 and really want to take advantage of the 64-bit. If anyone has any information it would be greatly appreciated.