Prove that no pair of the following groups of order 8: I8 (congruence class mod 8), I4 x I2, I2 x I2 x I2, D8 (dihedral group), Q are isomorphic.

The link http://www.mathhelpforum.com/math-he...tml#post392182 shows how D8 and Q are not isomorphic, but I have no idea how to prove the rest of the pairs are not isomorphic.