There are plenty of ISP's who will provide a download service without restriction. I find 512k adequate and many sites tend to restrict download speeds to much below this level (or there is a restriction somewhere). Daughter has had no problems downloading films overnight. The maximum speed of your service and whether you are restricted on downloads is all a matter of price. The cheapest unlimited 512k service I have heard of is at £17.50 per month. I use, and have no complaint with
this lot at £22.50/month and there are plenty of others.
P.P.
P.S. I should add that my 512k link regularly runs our three desktop machines, my trusty laptop AND my iPAQ simultaneously through my wireless LAN without any problems whatsoever!