preflop hand combinations

[muckyouraces]

How many differenent preflop (2 hole card) hand combinations are there?

[jay_shark]

52*51/2=1326 possible combinations of 2-card hands .

[rufus]

But all of those fit into one of 169 categories:
78 suited
78 unsuited unpair
13 pairs

With holdings in each category functionally equivalent to each other from the single player's perspective.