The 80gb's emulator was changed to make its price cheaper.

To replace the hard drive is legal and u can upgrade ur ps3 up to 250gb hdd space.

Its a bit quieter than a computer.

ps3 has this program called folding@home to help to do cancer research. u dont have to do anything for that, if u feel like letting ur ps3 help in processing then just turn on folding@home u will need ur ps3 to be connected to the internet for this.

The apperance of both 60gb and 80gb is the same...not sure about the weight.

On my 60gb i can play all my ps1 and ps2 games perfectly note: my ps3 is updated to the latest firmware making it have a better backward compatibility.