if you are into alternatives to ADSL, vodafone have got their act together technically for their usb modem internet. contracts range from 20e to 46e. the 20e euro a month gives 1Gb super quick (7Mb p/s) then 125kb p/s unlimited thereafter (download movies etc overnight) and you can opt out any month.
Again it depends where you are. Vodafone coverage here is rubbish. There are big chunks of Spain with very little coverage. But then a lot of people in rural Spain don't even have a computer!