Thanks Bento, I will take a look at True20. I've heard good things about it, but just haven't tried it myself yet. The adept sounds interesting. But from the sounds of it, how much is truly player controlled and how much is GM controlled. I am not sure that I, as a player, would want what power I worked for to be determined by the solely by the GM for an adventure. I may not be fully understanding what you are saying though. (heh, I know, get the book

)
DiamondB, One of the things I have considered doing is revamping prestige classes so that they are available MUCH earlier than normal, to give the players specifics to aim towards. For instance, there are different forms of martial arts, each one giving a bonus as a feat. Then they can study a specific school further by taking a prestige class associated with that school (say, starting at 3rd or 4th level). I think this runs pretty close to the idea of advanced classes in D20 Modern.
As for the magic, I merged it all into one type so that there aren't extra spellcaster classes running around, and to simplify things because it gets a whole lot more difficult with the magic house rules I am developing. I am using a gemstone based system I came up with in a 2nd edition campaign (same campaign actually, just moving it to D20, this was prior to the Demonwars Saga by Salvatore). In this system, you only start with four schools of magic. You can then use your bonus feats (which will be increased from the UA version) to acquire additional schools, specialize in schools, and take domains if the caster wishes. This is very much a work in progress and will give the player lots of choices... maybe too many choices. But that is why I am giving myself a lot of time before I start passing out info to players.
Thanks for the input! I really hope to get some good ideas from this thread to work into the campaign world.