i just know the software update for my 4g, now i found a blog told us how to download and install software update on the Motorola Atrix 4G.
following is the steps:
AT&T Motorola ATRIX 4G Software Update
AT&T Motorola ATRIX 4G Software Update | AT&T Cell Phones | Blog about att phones.
Tutorial:How to Root AT&T Motorola Atrix 4G