iPhone software update

I have a first generation iPhone, trying to download the latest update. I have tried unsuccessfully at least two dozen times to download the update, each time it fails and the error relates to my settings and network connection. (Why it starts over each time and wont resume where it left off is another question...) I have a satellite internet service (my husband successfully downloaded the update on the same internet service), am using iTunes 8, and have looked on this discussion page for resolution. One post directed another user with the same problem to an external link but the fix seemed to specifically be for people using the 3G iPhone. Any suggestions? I am at my wits END!
iMac Mac OS X (10.5.5)