There are many different kinds of wounds on strings (wrongly phrased perhaps as I don't really know what wound is) - some that I've seen are nickel wound, flatwound and something like roundwound. Now what is really the difference between these kinds of strings? Does it make much of a difference to sound? Their lasting perhaps? Price? Please enlighten me! Oh and I also came over some strings named Olympia. They're extremely cheap compared to what I use now (Olympia 130 NOK, D'addario 450NOK). This brand, is it any good?