Just felt I would put in my 2 cents worth. I have Henckel's and love them. Sure there are others and I'm sure most are good. You really want to have forged with the steel going all the way through the handle. Hold the knife and see how it feels in you hand, and yes buy just one good one if that is all you can afford.
I prefer a 10 inch chef knife for all around kitchen use, I use it more than any other I have. It's not good for slicing, so that should be your second knife.
And yes sharp is very important! I don't know about the sharpener mentioned above, but I have a Warthog. Cost me about a hundred at a boat show. Kind of funny looking, but it works great. Fast and simple to use.
Stay away from stainless cause it does not hold an edge, and never never use an electric grinding type, you will loose the temper in the steel.