Thanks, Mobile.

I'm leaning heavily towards the new chainring route. Looks like the 39T in the proper size would run me $35. So, I'll continue getting in shape and tackling the hills with the 42T and maybe pick up the 39T for grins and give it a shot, especially if the 2 are interchangeable by simply unscrewing 5 bolts and swapping the rings; would be a nice and easy way to expand my options if I knew I was going to be riding flatter or hillier terrain!