looks like people are running uncapped 5100's.
this place has some software and forums that might help.
they sell a modded 5100 kit with a preinstalled pin header, programmer, Software (on CD), and firmware.

hxxp://www.tcniso.net/forum/
hxxp://www.tcniso.net/Nav/Software/

from what i read elsewhere,
you can run a TFTP sever on your computer, login to the modem and tell the modem where to get the config file ( from your sever) then reboot and let it pull the config. that will stop the modem from pulling the wrong (lol) config file from your isp. get a MAC sniffer and use a MAC address thats not on your node and dont use your isp's mail servers or dns.
there is software for everything, including config file sniffers.
maybe some places to dl them, if you beg the right people…lol.
again, just from what i read. i never uncapped before.
i cant find the other links now, but people are uncapping 5100's and the info is out there.

how many options for broadband do you have?
at the very least, when you get caught, you will recieve an instant perma-ban from your isp.
worse case senario would be perma-ban + legal action.
i dont think its worth the risk.
4meg upload is tempting tho. 😄

@seedym:

When 'surfing', stop/pause/reduce downloads and reduce upload to half ie 15Kb/sec. Doesn't effect your surfing speed plus it also helps your ratio.

i'd try leaving upload alone or at 80% first, then lower it later if you have to.
i leave mine at about 80% all the time and never have any slow downs.

nice post.
congrats on fixing your ratio problem and thanks for your uploads. 🙂