Well looks like the Druid filled in for me. (Btw I ignore all Summon Spells. Heralds have that ability don'tcha know?

) Thanks Joseph.
Okay well the Paladin/Monk book probably won't be out until late 2003, since it will be the LAST Handbook to be released.
Silver Knights also tend to fight undead, but basically Dru was right, in that they are more specialize in fighting demon/devils and elementals. If you were to compare the Knight of the Chalice to Silver Knight, you'd see that a Silver Knight is NOT only much easier to get into, requirement wise, they do MORE against outsiders than most.
(Btw, Druid a revision eh? Not to heavy, I kind of like the way the class was done before too? I mean if you change "turn Titanspawn" fine, but not the Blade abilities I'd hope...)
ALL the Orders are 10 level Pr-classes (Meaning that if some nice developer wanted to, we could have Epic level Mithril Knight, Silver Knight, Iron Knight and Gold Knights running around!

)
Minium level for these Pr-classes ranges from 5-7 level, if your Paladin anyway. Straight clerics could also qualify for one of the Orders, Iron. Silver and Mithril MIGHT be out of their league, since Silver requires "Detect Evil" as a spell-like ability, and Mithril requires "Smite evil" as a supernatural ability. Gold requires ability to lay on hands and remove disease abilities.
But since you DID ask for the requirements, here they are:
Mithril Knight: (Subject to the revision I'm sure)
Base Attack Bonus +6
Alignment: LG
Feats: Weapon Focus: Longsword
Skills: Craft (weapon smithing) 8 ranks, Diplomacy 5 ranks, Knowledge (religion) 5 ranks
Special: Must have the supernatural ability "Smite Evil"
Silver Knight:
Base Attack Bonus: +6
Alignment: LG
Deity: Corean
Skills: Knowledge (arcana) 2 ranks, Knowledge (religion) 4 ranks, Knowledge (planes) 2 ranks, Spellcraft 3 ranks
Special: Must be a member of the Order of Silver.
Special: Must have Detect Evil as a Spell-like ability.
Gold Knight
Base Attack Bonus: +5
Alignment: LG
Deity: Corean
Skills: Concentration 4 ranks, Heal 8 ranks, Knowledge (religion) 3 ranks
Spellcasting: Must be able to cast cure light wounds
Special: Must be a part of the Order of Gold
Special: Must have the ability to lay on hands and remove disease
Iron Knight
Alignment: LG
Deity: Corean
Skills: Craft (armorsmith or weaponsmith) 8 ranks, Craft (seige weaponry) 3 ranks, Knowledge (architecture and engineering) 2 ranks, Knowledge (religion) 3 ranks, Profession (seige engineer) 3 ranks
Feats, Skill focus (Craft Armorsmith or Weaponsmith)
Spellcasting: Must be able to cast the divine spell magic weapon
Special: Must be a part of the Order of Iron.