Ryan,
Just bear in mind that a 3Mbps (megabits) line translates to a real world download speed of roughly 300KB (kilobytes) per second. The "speedboost" that Comcast likes to talk about is only good for about a 1sec burst and not useful for file downloads. So for a 100MB file it would take just under 5 minutes to download, assuming 100% network efficiency. The other thing to consider is that if you're on a wireless network you may simply be limited by proximity and not your actual line speed. I'd run some tests using a utility like Speedtest.net - The Global Broadband Speed Test and see what you're getting for actual, real world speed wherever you normally sit to use your computer. I get my full rated speed (2MB/s) only if my laptop is sitting on the desk next to my router, it's generally about half that if I'm in the living room.