For D20 Arthurian goodness, go to RPGNow or your FLGS and take a look at Legends of Excalibur by RPGObjects.
Caveat: Yes, I worked on the book.
That having been said, when my copy of the hardcover edition arrived in my hot little hands, I pulled it out of the package and this cynical old bastard was astounded. First things first... Beautiful cover (I know... who cares? Right? But BOY is that a beautiful cover). Secondly, full color maps on the inside covers (both pages when you open the book, you have two maps immediately staring you in the face, and the back cover, and inside page... again, beautifully done cartography by Clayton Bunce, though there was another name Chuck gave me for the maps, and I can't remember it, at the moment). Next, you get into the book, and it's fairly obvious that Mr. Rice is at the very least a great fan of the Arthurian mythos, and has done his homework. The classes in the book are well researched, and well balanced, and represent courtiers, nobles (the noble class in here is probably the best handling of nobles in a D20 RPG I've seen.. yeah... I think it is), Skalds, and KNIGHTS... there's the bit, ain't it? Knights. You want knights? Well... Here... let me back up, just a moment and just give you a list of the classes in the book. I hope Chuck and Chris will forgive me for presuming, but, here we go.
New Core Classes:
Fool
Hedge Mage
Hermit
Knight
Minstrel
Noble
Priest
Robber Baron
Skald
Yeoman
New Prestige Classes
Alchemist
Berserker
Changeling
Court Mage
Crusader
Enchantress
Lady of the Lake
Quest Knight
Saint
Spectral Knights
Black Knight
Blue Knight
Green Knight
Purple Knight
Red Knight
White Knight
Add to all that, some new feats, new skills, a new magic system (to represent the ley lines so prevalent in Arthurian mythos) .... Well.... Suffice it to say, it's worth getting, in my not so humble and possibly biased opinion.
Now... I don't make a thing off of the sales of this book. My part of it is done and over with. I can't imagine anyone being disappointed by purchasing this book looking for a good Arthurian campaign.