You can run at least 3.0/3.1 but you will need to upgrade the rom from 1.3 to 3.1! but i dont see why you would do this as it will most likely make a LOT of games non working anymore! the A500 isnt very usable as anything more then old demos/games but if you have a lot of money to burn be my guest and upgrade it ;-) id personaly rather buy a A1200 if i were you as theyre quite cheap and will run 3.0 without any modifications.
