I have satalite internet for my home (can't afford for the RV yet)and it is not too bad. If your used to dialing up via a modem, it is much faster. If you have ever used a cable modem or DSL, it is slower than that, but not by much. You do not need a analog line like the satalite internet systems in the past. My home system is about 100.00/month for standard satalite TV and Internet combo.
If you wan't serious speed, I believe there is a satallite based system out there that will run equal to T1 speeds (equivilant to downloading a song in 10 seconds) to your RV. I am looking for the link and will get it to you if I find it. I've seen it mounted on a few semi trucks.
go to www.motosat.com to find out about the datastrom system from hughes. You do not need a land line and for only four grand plus installation plus $99 a month you can have internet access anywhere on the continent. It is faster than dial-up but not a sceamer.