To answer your original question Dereck...
The Knight Hospitaller were a holy order of the Kingdom of Jerusalem durring the time of the Crusades (1095-1291).
I do not know all that much about the Hospitallers as I am more intrested in their brothers the Knights Templar. Unfourtunatly the two orders did not treat eachother like brothers, and often hated each other... (Sometime I don't understand the things people do...)
They grew to be a large order, and quite powerful. The Grand Master was the order's leader.
They were originally created to build and work in hospitals, but they also trained Knights to aid the Crusaders.
That is a rough history of the Hospitallers... or what I know of them.
Hope that was helpful! 
The Knoghs of St John or Knights Hospitallers were originally created to provide protection for pilgrims going to Jerusalem by escorting them. From this grew the practice of the Knights providing hospitality in the form of overnight rest places, safer and better than the local inns. This is where the Hospitallers title came from. Over time, they also provided medical treatment at the stopover points and, eventually, quite sophisticated medical and surgical treatment, both on and around the battlefield and elsewhere. The old Knights Hospitaller Hospital in Valetta, Malta, is very impressive and has the largest mediaeval arched roof in Europe. They were also fiercesome fighting knights, too, and became very powerful politicially in mediaeval Europe.
Their official website (the order still exists but not with its original functions of course) is here:
http://www.knightshospitallers.com/history.htm
