I thought I'd highlight the recent movie called Kindom of Heaven. First off, I'm sure all Gladiator fans out there know the genius and authenticity of Ridley Scott's work. KOH certainly ranks up there with Gladiator.
The story is that of the tension between the Crusaders (Templars) and the Arabs in the Holy Land. Orlando Bloom plays an illigitimate blackshith who just recently lost his wife. Back from the holy land rides his father (Liam Neeson) who he has never known. His father's pleads with Ballian to follow him back to the holy land and be his heir to the small hamlet where Neeson is Lord. The rest of the movie follows the battles and trials of the struggle including a siege of Jerusalem.
I would encourage you to watch this movie, that is if you are allowed to see it, for it is a great inspiration for MOCs. The armor, weapons and clothing are very authentic, not to mention the trebuchets and siege towers.
Thats my humble opinion.