Does that mean that one person could buy a game and several of his/her friends could put the game on their system?

And if so, do you think that Microsoft will experience any significant decrease in software sales?

I apologize if this has already been asked in a thread, I did not see anything on this topic though.

No, they attach your Gamertag to your purchases. You could share a Gamertag though, i think. The game could be on the hard drive but unless you are under the Gamertag that purchased it, you cannot play it.

Games save to your hard drive you can play any game bought on your hard drive.

No. If anything, the game will be played by less people. If it's played by any system except the one it was downloaded for, it won't work unless that 2nd console and gamertag are online. You'd have to recover the gamertag and re-download the game too.

If anything, it'd be easier to buy a disc and pass it around. And NOBODY adds to my gamerscore but me!

Oh ok well that makes sense, I just got to thinking about that and was curious as to how they would do that. I was thinking they could do a key for each game like they do for Office and such, but I was unsure if there was anything to prevent people sharing games with full download.