As for broadband, all providers offer some version of card, or usb device for easy selection based on what computers you need. For example, one can sign up for sprint Sero for 49$ a month, unlimited EVDO and either select and USB dongle type device, or a pc card. If one ONLY had a pc with pc card slot, or express card slot, then that might be the best solution.

The create a bridge and router essentially at the desktop pc, is pretty easy. ICS could easily be enabled to source the USB internet broadband connection and send it to the router via the ethernet on the pc. Then, the router works as usuall and the print should too. Your just offering a different internet source to the desktop pc, (which is this case is really just acting like the modem)

As for DSL, there is usually just ONE true providor, the telco. If ATT is your telco in that area, I don't see why they don't offer DSL, one building shouldn't be an issue it is the local CLEC and the switch you are at. I can assure you Earthlink is simply reselling the ATT circuit, as/or is covad. They may have their OWN pipe coming in to the local switch, but the lines are the local carrier. If you HAD and liked the ATT DSL I would further pursue that.

Or, go SERO (check your coverage at home) and then you get a home and mobile solution