This was from 2007 about Microsoft testing out using gamerscore in a similar way to a Club Nintendo or any other special status club.
http://xbox.about.com/b/2007/02/07/m...re-rewards.htm
I would assume they were never really going to do a 1:1 conversion on score to spendable points since it would end up being too costly for them or encourage hacking/boosting of the gamerscore. There were a bunch of ideas floating around of what Microsoft might do to help promote and get people interested in the avatar store when it was released.