another problem of the ramjet is that matter collects in front of the magnetic field slowing you down. You can't just turn off the field to let the matter disperse because at relativistic speeds the collision energies would be lethal. I believe Ned already commented on that problem.
I'm only going to hit on the methods of travel, at the moment, because I find them the most interesting. As far as sublight goes I see several general possibilities: 1) Bussard interstellar ramjet. Razd has already covered this so I will let it stand as stated. 2) Generation ship, the difficulty is what life forms do you take? There are also social problems, Robert Heinlein wrote a fairly well thought out juvenile novel about this. Unfortuneately my library is in storage and since that beating I took I'm having some quirky memory problems. So once again I don't remember the title. 3) Solar sail, this becomes more inefficent as you get future from the sun. Arthur C. Clarke wrote a short story called "sunjammer" that covered a lot of the technical issues. Also the first chapter of "The mote in god's eye" has a good discription of one in use. 4) Laser launcher with or without solar sails, Larry Nivens known world stories cover this fairly completely. You would need a very large battery of lasers but, as I understand it something called the near field effect would limit attenuation of the beams. Making them useful over a greater distance. 5) Ion drive, best description was a boron type, used in system, in the Donald Moffit novel "The Jupiter Theft". Advantage is very low fuel consumption. Disadvantage is very low acceleration ( about one-hundredth of a gee). You would have to build it in orbit.
Now onto the faster than light drives. As I understand it there are two first class candidates: 1) A space distorting drive, this would compress the space in front of you and expand the space in back of you. The advantage is that you could cover distance, in excess of light speed limitations, without violating general relativeity. Basically you are "surfing" on a wave of space. 2) Either create or pass through a wormhole. Energy requirements to create one would be grim, however since naked singularities are theoritically possible they should occur naturally. You just have to get to one.