As I read through some of this thread a thought strikes me -
There really are two schools of thought at play here (and no, I will NOT use "old" or "new" here lol) - one that likes RPG systems to give very basic mechanics and asks that individual GMs take the burden of tailoring/interpreting specific circumstances as they go, and another school of thought that believes that the clarity of specific rules for specific instances should appear "on the page," which necessitates a rule-intensive RPG system.
I'll say this - I don't think there is a right or wrong here, just differences in tastes. Like Treebore and Tank I am a proponent for C&C, my game system of choice, and I echo the things they have said. That's not to say there won't be people who come from the 2nd school of thought who will not find C&C attractive, and would not enjoy the necessity of the GM (CK in C&C) undertaking the burden of figuring out what to do in situations like the whirlwind mentioned above. That's cool

- there are plenty of d20 systems to play, and I for one won't begrudge anyone who prefers 3.x if that's their taste. There are also plenty of people from the rules-lite school who just won't like some specifics of C&C that are too "unified," or similar to d20, and so there's always 1E, OD&D, OSRIC, etc.
To the OP - I think Treebore got you directed to the TLG boards and I think people have probably answered, but I will add that I think Greyhawk would be easier to jump into with C&C, Eberron would take more work and thought as it's geared in a very crunch-heavy way towards 3.5.