500mb is enough, unless u on youtube everyday...i am us ing 500mb, house and office got wifi, and most of the hsopping complex do have wifi as well, i only used up to 12% of my 500mb, according to watchdog, yet to receive bill, will verify if watch dog 3g is accurate with the bill later..and fyi, my usage on internet is only to read desire thread, facebook, including loading photo, emails, online banking, google talk, and msn..out of 30days, i used only 12%...