Since I was having some troubles with the gears I have already followed some of your advices. I have a seven gear hub 11-24 (well, it is really a nine gear hub but the shifters are only 7 speeds so the two bigger rings are not in use).

I have yet to see how it works.

I have also ordered o new front wheel -26 inches- since according to most of you no improvement would come from the 700c wheels.

The front wheel I' ve been using is 10 years old and it produces some loud cracking noise according to my LBS it's the axle which is gone. BUt it is so old that they aren't any longer available in that measure.