lnn2 wrote on 01/23/07 at 01:34:59:
i currently play 3. Nf3 against both 2... c6 and 2... e6, entering the line 1. d4 d5 2. c4 e6 3. Nf3 c6 4. Qc2, you don't need to know much theory here, only that if your opponent plays 4... dxc4, just play Qxc4, develop the bishops to g5 and d3 and put your queen's knight on d2, I'm not sure if this is still advantageous for White, has Timofeev and Galkin (Black specialists in the Marshall/Noteboom) found an equaliser already?!
If so, then White can switch to a Catalan set-up with good chances for an edge, but its not terribly relevant if you aren't facing a knowledgeable titled player, as 90% of your opponents are likely to play a Stonewall or a QGD (Be7) setup instead, both of which are known to be inferior choices in this move-order.
Another benefit of 1. d4 d5 2. c4 e6 3. Nf3 is that it gives you extra low-maintenance options against the Tarrasch defence, you can also avoid lines with the early ...c4 which can be hard to play against without experience, and the hennig-schara gambit. But you need to learn 5. Bg5/5. Bf4 main lines , Ragozin and Vienna for a fully viable repertoire.
You can play 3. Nc3 and still avoid the Hennig-Scharra, if you are willing to play against the Semi-Tarrasch. Answer 3...c5 with 4. Nf3. Black can have a Semi-Tarrasch with 4...Nf6; if he intends a proper Tarrasch he has to play 4...Nc6, and you then play 5. cxd5, avoiding the gambit. As I dimly recall, Schiller has a Tarrasch repertoire book advocating 4. Nf3 cxd4 but I don't think that Black is O.K. there.
As for the Tarrasch with an early ...c4, are you referring to the Swedish Variation? But in that, White's knight is already on f3, isn't it?
You're right that if you play 3. Nf3: you allow the Ragozin/Vienna. There is a pile of theory to learn there. You also permit the Semi-Tarrasch. But in none of these cases does White surrender his += birthright.
My answer to the original post is that if you play 3. Nc3, you have to have something prepared against the Triangle. Either prepare something against the Noteboom, or book up on 4. e4.
One little thing not observed so far is that if 3. Nc3 is your poison against the QGD, you MUST allow the Nimzo, since Black can reach his QGD via 1....Nf6, 2...e6, 3...d5. On the other hand, if you like 3. Nf3 against the QGD, you MUST NOT allow the Nimzo, since 3. Nc3 versus the Black moves I just gave lands in in the QGD with the "wrong" knight out.