Overrated:

Sachin Tendulkar (he does not totally deserve the fame he has)

Rahul Dravid (he probably did play well during his days, but he has not lived up to expectations; it is waste to still expect from him)

I do not think Jacques Kallis is overrated; he is the match winner. You can not win the match all the times. Neither is Muralitharan.

Underrated:

Chris Cairns

Saqlain Mustaq

Stephen Flemming (oh my god, I love him when he gets going)