I agree with Gwalk900, the best would be to invest in a good router with traffic management/measuring software. It will save you money in the long run, will give you much more control, show you what data has been used, and by what devices in most cases. Also, a decent wireless router will give you much better wifi coverage in your home than the Exede combined modem/router.
If you'd like to add our WiFi Modem, it's an extra $5/mo. If you're in an area where you can get our 25 Mbps 'Boost 25' service, it'd be another $5/mo. You can enter your zip code on exede.com to see what's available in your area, or just check your account on myexede.net.