Originally Posted by Avid (Post 1914475)

We're pleased to introduce Pro Tools Express software—a new streamlined, 16-track version of Pro Tools 10 included with the 3rd gen Mbox and Mbox Mini at no extra charge, starting March 21, 2012. Pro Tools Express includes many of the same features of Pro Tools 10, though it doesn’t include the new Clip Gain feature, Beat Detective, or the Timecode Ruler—and it’s limited to a maximum of 16 stereo audio tracks.

For a detailed list of differences in Pro Tools versions, see the Pro Tools Software Comparison page

Pro Tools Express software includes the virtual instruments, sound processing, effects, and utility plug-ins listed here:
Pro Tools Express Bundled Software

If you have questions about Pro Tools Express, please check out the Pro Tools Express FAQ

For help with Activation or Installation see the Pro Tools Express Installation Overview

Akai Professional & M-Audio Interfaces
Support and downloads for all of the Pro Tools Express software included with the InMusic Brands M-Audio and Akai interfaces is provided by InMusic, not by Avid. You can get downloads and help from their website here:
Installing and Authorizing Avid Pro Tools Express
www.inmusicbrands.com/ptex

On the M-Audio site, you can also find some tech help with this Knowledge Base article:
M-Audio M-Track - Setup with Pro Tools Express