Phew, that's a tough one. It's definitely true, some people won't take you not drinking so well. I've just told a few very good friends about this and currently maneuvre myself around the others. As long as you have one or two friends around you who know about it and can gracefully help you out of sticky situations, it should be fine. As long as you got a drink on you that just might be alcoholic, not many people will ask any further. Of course, bar crawls are kind of out of the picture (because you kind of bring your non-drinking up by ordering non-alcohol).

I think that to most people it is just how much of a "thing" you are about to make of your not drinking - they just don't want to be reminded that it might be problematic, which "we" kind of do by bringing our decision up. In that case taking it low-key, with one or two confidantes around, should serve you well.

I still don't think you should feel pressured to accomodate your drinking friends like that, but I do understand you want to keep them.