Geron Raveneye said:
Got to say, in the case of that kind of cross-conversion, I'd recommend C&C over the classic D&D. Less problematic to convert 3E stuff to C&C, really.
Which is a "pro" in Classic's column - when you've got 25 years of TSR-quality material to draw from versus not-quite-10 years worth of d20 quality.
C&C gets a lot of good attention; I haven't given it a whirl myself, but a lot of folks love it. As far as the real deal goes, though, I'd have to go with BECMI over RC, for a couple of reasons.
First, your players will be able to
find it. Mentzer Basic Sets can be had in good shape on eBay for 15 bucks or less (no "hunting" required, there are at least 4 copies up as we speak), where a RC in decent shape will go for anywhere between 30 and 60, depending on whether the collector market has had its fiber that day, and that's if you can find one without getting it sniped out from under you. (Now, of course,
you want a copy, but you're the DM.

)
Second, Mentzer spoon-feeds players the complexity, in a good way. As a new player, having a friendly little red book with just the stuff you need is a big plus. And the tutorial stuff in there is top-notch; the RPG industry really hasn't come up with anything this good for teaching the game since.
And lastly, RC doesn't have Bargle and Aleena. Total, crushing win for BECMI, hands down.
(FWIW, I actually run B/X with some tidbits stolen from BECMI, RC, AD&D, and even HackMaster. Mentzer Basic is the reigning champ when it comes to
teaching the game, but I find Moldvay a better-organized book to refer to during play - and the less time I spend with my nose in the book during a session, the better.)