It's worth noting that upgrading the operating system won't affect what games work on your A600 much, it's a pretty basic machine and you have to go out of your way to do more than add the extra 1Mb of memory.
Some old games require 1/2Mb of fast mem, adding the extra 1Mb to an A600 will make 2Mb of chip mem, and no fast, so additional patching may be needed ...
