Angus the only folks I know who practice extensively with the two-handed swords are the gents at the Royal Armory you saw on the History Channel.

There are more than one type of two-handed and hand-and-a-half swords. Some have a handgrip below the crosshilt, and some don't.

I am not well enough trained in fencing to explain all the ins and outs of rapier or small sword versus broadsword, but they are used in vastly different ways, and both are quite effective it the swordsman knows his trade and has the determination to press an attack intelligently.

If I can find any sites to compare the two fighting styles, I will post them here.