Hello Speedygonzi, Wendanne,
First, let me say that Berlin is a wonderful place to live with a young child/children. Of the big cities known to me it is by far the most child-friendly. It is incredibly easy to move around (use public transport or bike -- the pavements are so wide you can ride along the pavement with the little one(s)), there are great parks and playgrounds, more child-oriented activities than you could imagine (puppet theatres, special events at museums, children's music groups, art workshops, etc., etc., etc.)
One general thought is that the more prepared you are to enter into the spirit of the place the easier it will be. Berlin's attitude is quite bohemian, somewhat anti-bourgeois (saving the planet, banning nukes), big on culture and nightlife. If your idea of the good life, is watching the telly, mowing the lawn and washing the car at the weekend, this may not be the place for you -- you'll find plenty of that in the rest of Germany.

With that in mind, I'd endorse what Cedarwoods says. For obvious historical reasons, Berlin isn't surrounded by lots of 'burbs full of single-family houses. The villas in
Zehlendorf and Dahlem are huge and magnificent, but wouldn't be my first choice. If you want to enjoy the woods or the Wannsee, it's easy enough to get out there on the weekend.
Most Berliners rent apartments and there are great ones out there at prices that seem a complete give-away by the standards of the U.S. and the south of England. I'm living at the moment in a huge apartment with twelve-foot ceilings (!) in a non-renovated building. OK, it's quite ramshackle but the people I'm renting it from have made it very comfortable. I like it much more than the place I rented in Cambridge, Massachusetts for twice the money.
I know Prenzlauer Berg best, because that is where my wife and daughter are living and it is great for small children (and full of them!). But I wouldn't say that you *had* to live there. If I were being sent by my company I would certainly also be looking in Charlottenburg (which is, traditionally, the best area) but, if I didn't have much money, I wouldn't turn up my nose at any area. There are nice buildings, safe streets, good shops, playgrounds, etc. pretty much everywhere.
Some warnings, though.
Germany is NOT set up for working mothers. The school day is short and you'd be astonished how often school is cancelled (Hitzefrei, Kaeltefrei -- you name it!) and you have to hunt for childcare. Very few Germans are in that cycle: have the kids, work all hours to pay for the childcare so that you can go back to work ... If you do want to go down that route, take a lot of advice. On the other hand, you can live here very well on not that much money, so, if you're tempted to take some time to enjoy the kids while they're young, it's more practical than in most places.
Berlin schools certainly have problems. My daughter is in the S.I.S. (Staatliche Internationale Schule/Nelson Mandela Schule). It's a good school, very over-subsribed and has serious difficulties. A lot has to do with Berlin's terrible financial situation and the legacy of re-unification (there are many former East German teachers in the system who are, to be frank, not very good). If you're putting your child into the state system, be very careful. I have heard mixed reports about kindergartens but I can strongly recommend the Waldorf kindergarten in Prenzlauer Berg (see Cedarwoods' post).
Finally, I'd be very careful about establishing any kind of a business without all the necessary paper-work, least of all one involving children. Germans are very keen on the letter of the law (does that surprise you?

) and if, God forbid, anything were to go wrong, I think you'd find yourself in big trouble.