Signal issue

First of all, I apologize if this is the wrong section.. I'm a newbie, and this seemed like the best place to ask this question.

Ok, here's the deal: In my area, I can only get mobile broadband. While I have gotten it to work on my pc, I can't get a strong signal without sticking an antenna out the window. I can't figure why the signal is so bad.. I'm in an area that is supposed to get max reception and speed, but that doesn't happen even with the antenna. I hold a steady 80% with the antenna out the window which isn't shabby, but I'm suppose to be getting a max of 3.2 mb/s, but I only get 1.2-1.5 at best at -80 dbm average(drops to -77 at times). So signal loss/ noise is high- but that's to be expected of an RG-58 Coax cable I suppose.. those cables suck..

My question is: Is there a way to get that 80% signal(minus the noise) from inside my house? If I can get rid of that noise, and get that signal, then my speed will be wonderful! I've looked at the ARC Freedom antennas, and others, but I don't know if they will work. The antenna I have doesn't even do much inside.. but then it's only 7 dbm gain, so nothing too spectacular really.. Or should I go with a router? If so, what type/ what do I need(equipment wise)/ need to do in order to set it up? Will it be able to pierce the signal blocking walls of my house? I've also heard rumors that making an antenna out of a coffee can is supposed to be really effective.. is there any truth to that? I can lend that link if needed- it's an instructable.com article...

I can't cut any holes in the walls, just to let ya'll know. If I could, then I wouldn't even be asking this.. I'd just install a satellite on my roof..

Sorry for the long post, but I wanted to make sure I got everything down.. I don't think I forgot anything. Thanks in advance for advice!

-Chromos