Just my 2 cents, but at this point I think it is a must. for much of what newtekie said to start with, but he didn't expand his last point. The only reason games are still claim no more than 2 GB is that is a limit for an app. in Windows XP. This is still tacked onto games for those die hard DX9 gamers out there. This, like the 16-bit and 8-bit support Newtekie brought up, will be phased out in say the next 2 years. Once DX9 is no longer a support requirement for a game, 32-bit OS will die along with it soon after. Don't let rumors get you. There is not need to go up to 128-bit for processors. Doesn't matter what the OS claims to support, AMD and Intel are the ones who decide if that will be what is available on the processor market. And true backwards compatibility is impossible when the core design of something is changes. There were drastic changes between XP to Vista and Vista to 7. You are just going to have to hope your obscure software can be replaced or updated by the creator.