Mr. T. Tech--50MB is a pretty small file these days. (you could not even download WinXP SP3 with that limitation).
Comcast has been know to throttle back the amount of downloads that people who are considered to download "excessively" can do. You might phone Comcast and ask if that is the problem. Of course, if that is not the problem, you can ask Comcast's help.
http://blog.wired.com/monkeybites/20...t-custome.html
http://www.maximumpc.com/article/com...verage_charges