Ubuntu Networking :: Last Ditch Effort To Get Wired/Wireless Working?

I posted here a couple weeks ago about my wireless issues and someone suggested I download an update of firmware for my Broadcom wireless card. The problem is I can't even connect to the Internet with a wired/Auto Ethernet connection in order to download said firmware. I tried downloading it on a different computer then using a flash drive to transfer it, but when I opened it on my computer, a message popped up saying the files were corrupted (this happens every time I try to install any program/update from a flash drive). So I tried today to use the wired connection to download the firmware but a) it wouldn't recognize the connection, so I deleted the AutoEthernet connection, rebooted, and activated the new one, as per the solution I'd read in a different thread on the forums. The wired connection worked, but only intermittently--it disconnects about every minute or so--and even when I'm connected, Firefox won't load any pages so I still can't get the update I need for my card.

I feel like I'm out of options here--I've been having this problem for about 7 months and I, or my much more Linux-savvy acquaintance, have not been able to figure out the problem. I'm thinking the only solution at this point is to go back to running Windows, which I really don't want to have to do.