What to play against 3. c4?

Okay, today my opponent played 3. c4!?  I am not really sure what to give this idea, so I give it the !?  I am interested in seeking what players on here typically play.

Here was my idea today - 

http://www.chess.com/livechess/game?id=1223670132

I secured two wins with this idea, but since it is new for me, I wanted to see what Rybka thought.  Rybka is recommending to take the e4 pawn and then develop accordingly.  My idea was a bit more conservative - playing ...Nf6 to provoke e5, and then play for ...Nd7 and ...c5 with pressure on his center.  

Ideas?  Should I automatically take on e4?  Or are there other ideas that anyone here typically tries?

3...Nf6?! is very risky, as after 4.e5 Nfd7 5.c5 the center is closed and white has a large space advantage on both sides of the board.  I would say 3...dxe4 is definitely more accurate - not because the pawn is free (your pawn on e4 will likely fall eventually anyway), but because it achieves the purpose of the French.  In the early stages of the French, your goal is to fight the e-pawn for control of the light squares.  The main lines involve white either trading on d5 or playing e5, which are both concessions on white's part, but 3.c4 dxe5 demonstrates why white gives in.  The position looks like a Rubinstein Variation, but what exactly does the c4-pawn do?  I don't know much about the Rubinstein, but I imagine black will use the d-file and possibly fianchetto the queen's bishop, with rapid development being a priority to capitolize on the tempo white wasted on c4.

I thought about c5, and I debated on b6 at that point.  

Believe it or not, c5 is considered ?! according to Rybka!  Rybka recommends cxd and it looks like Black has a choice between Bb4+ and Nb6, and White gets in dxe, with a half-pawn advantage.  

Now that I went ahead and took the pawn back with cxd exd, it is recommending Nc3 Nb6, Be7 and 0-0.  This is a .38 advantage to White according to the bot.

EDIT - looking further into that c5 line, after b6, Rybka is recommending a gambit with cxb c5 bxa Nc6.  It considers the line totally equal, with -.15 for Black.  I guess that is not TOTALLY equal, but close enough.

Always be careful analyzing lines with a computer - they excel in sharp positions, but tend to be less reliable in positional lines.  They also ignore some important practical considerations.  After 3...Nf6 4.e5 Nfd7 5.c5 b6 6.b4, it becomes clear that black will not be able to break through on the queenside.  From white's perspective, this is at worst equal, but when you consider that white can play to break open either side (or both sides) for an attack while black can do little more than sit and wait, it is clear that white will win more often than not.  Maybe Rybka is right - white's .15 lead in the analysis you gave may be better for white (perhaps my line only scores .05 for white), but I'd choose my line over Rybka's every time.  I do think the position after 6.cxb6 c5 looks nice for black, but sadly black can't force white to avoid 6.b4.

I also notice another promising option for white - rather than 5.c5, he can play 5.cxd5 exd5 which would likely also be in his favor (this must be better than the Exchange variation since white still has both center pawns, and the position is similar to those white aims for in the Colle System - 1.d4, 2.Nf3, 3.e3, etc.).

The cxd line was what I anticipated.  Thanks for the candid responses.  I am going to look into the exd lines, but wanted to get some input from others on here.