Thanks Sara Jayne - I-m still wading through all the information on Yarndex!
Is it safe to say that if the specified needle size and the substitute yarn gives you the same gauge swatch as the pattern, you´re good to go. And if not, you can play with needle sizes to get the gauge required by the pattern, and then you have to make sure that the yardage of the substitute yarn matches the amount called for in the pattern? ( that made sense to me, hope it does to all of you as well...
Thanks - I think I¨m really going to like it here! Karen