About pumps....the first time I used a new one I realized that the part with the holes in it had to be pulled apart and the presta valve stem piece put into place (if that makes any sense); actually a fellow rider showed me.

I sometimes use a CO2 to top off my road bike tire. I have one of the holders that lets me control the amount going into the tire. The thing I noticed with CO2's is that you need to be sure to check the tire inflation because the CO2 gas seems to leak out (or something) after sitting even overnight. Friends have mentioned this phenomena also.