" My question to you is this; I have pretty much settled on the Colle system for my opening but cannot find a defense that I like playing. I am not trying to be a Grand Master or anything I just want to be a good solid player. I've been thinking about the Tarrasch and the Modern. The Modern from what I've read can be used for just about any White opening which I guess is what I would prefer (I'm not sure that is aggressive enough for me). The Tarrasch is just an answer to Queen Pawn openings; then I would have to learn a defense for the King Pawn Openings."The Tarrasch is a good choice I think: active and solid, perhaps a bit more open than you might like. A good partner for the Tarrasch might be the Petroff; again a very open game as Black. The Queen's Gambit Accepted also has the same flavour; open and lots of IQP positions.
You can sort of play the Colle reversed against 1.d4; it's called the Semi-Slav. I've got a web-page somewhere (http://exeterchessclub.org.uk/content/playing-black-against-queens-pawn-openings) which gives a repertoire with it and the Stonewall Dutch (which starts off with the same "Colle Triangle"). The pure Colle Reversed isn't that great for Black (White normally gets in e3-e4 before you get in ...e6-e5) but the Semi-Slav and Stonewall enjoy a good solid reputation at all levels.
I used to play the Modern but gave it up; it's too hard for me and I used to get very different structures every game, and was losing games I didn't understand (always a bad sign). A set formation with ...g6 ...Bg7 ...c6 and ...d5 leads to the Gurgenidze against 1.e4 and (usually) a variation of the Grunfeld against 1.d4; but I don't much like either system for Black.
The defence which perhaps gives the most reliable and limited set of structures to play is the French; it comes closest I think to a system which is easier to play for Black than White (Kramnik claims the same about the Stonewall). I think the French fits alongside the Colle and Tarrasch/Semi-Slav quite well; it goes at about the same speed and you can play 1...e6 and 2...d5 no matter what White does as the first two moves: always a comfort!
Pete enquired further:
"Can you recommend good books on either the Dutch-Stonewall or the Semi- Slav?"I replied:
If there's not enough in the Playing Black against 1.d4 webpage for you...
There's a really nice little book, terribly out of date, but still useful, by Tim Harding. Queen's Gambit Declined: Semi-Slav. A library, a second-hand shop, or a friend might be able to supply it, if you don't have much left in the piggy bank after buying those books on the Modern. http://www.amazon.co.uk/exec/obidos/ASIN/0713424486/ A copy of QGD:SS with a look at Nunn's Chess Openings to bring you up to date should be all you need at our level.
If you are thinking about buying new books, the Starting Out series from Everyman I think are usually quite good. There are volumes on the Slav/Semi-Slav (which I haven't read, but Flear writes fine books and knows a lot about the Slav complex: NB not all of the book will be about the Semi-Slav with ...e6) and on the Dutch by MacDonald (which I own, and it's very good, but not all of it is about the Stonewall). http://www.amazon.co.uk/exec/obidos/ASIN/1857443934/ http://www.amazon.co.uk/exec/obidos/ASIN/1857443772/
A bigger theoretical book is Peter Wells on the Semi-Slav; but that is a book for real theory nuts. I haven't read it but it's reckoned a good book, although it's ten years old now. http://www.amazon.co.uk/exec/obidos/ASIN/0805032886/
The Bellin books for Batsford on the Dutch have good chapters on the Stonewall, http://www.amazon.co.uk/exec/obidos/ASIN/071343211X/ and http://www.amazon.co.uk/exec/obidos/ASIN/0713457600/, but if you're in for a book of that level you can't do better than Jacob Aagaard's monograph on the Stonewall. Aagaard always writes well and he's done everything you need to do for this line. However, it's pretty chewy material and he doesn't cover all the sidelines you need to know if your opponent doesn't want to play the Stonewall (like 2.Bg5). I think also that Aagaard has not played the line himself, just been asked to write a book about it. http://www.amazon.co.uk/exec/obidos/ASIN/1857442520/
So, with Aagaard, you'll need the MacDonald or the Pinski books http://www.amazon.co.uk/exec/obidos/ASIN/1857443071/ as well to fill out a Dutch repertoire, or a bit of time with an openings encyclopedia like Nunn's. Many players (like MacDonald) use the move order 1...e6 to dodge lines like 2.Bg5, but that means you have to play the French or some lesser defence.
A book I don't know at all: The Chess Advantage in Black and White by IM Larry Kaufman http://www.amazon.com/gp/product/0812935713/ recommends that Black play the Semi-Slav against 1.d4. It should be OK but a lot of the book will be wasted if you don't play the other lines. (Spanish Exchange, Berlin).