need help and advice on 4 bikes

pistol81

hi people,
iam new to all this and would love some help and advice on what bike is best. I have looked at 4 hard tail bikes, iam interested in cross country and general trial riding. the 4 bikes are;
cube acid 2010
focus killer bee 2010
cannondale trail sl4
khs alite 3000 2010

all these bikes are around £600-£700

if anyone has any hints, tips or advice it would be appreciated

thanks