How to choose a set of tyres
Usually, for a MTB hard tail, a 26 x 1.25 tire is the narrowest comfortable tire to ride. 

It is narrow enough to provide significant benefit to speed and rolling resistance, but not so narrow as to increase the probability of flats and rim damage. 

The continental tires you linked are a good choice. I would probably do the 26 x 1.3 version of that tire.