Some excerpts from the link regarding internals:

The poll showed Obama, an Illinois senator, leading among African-Americans by a better than 2-1 ratio. Clinton, a New York senator, led among whites by 2-1. Overall, that translates to nearly a 10-point lead for Obama.

The poll showed more than half the likely vote coming from African-Americans -- 54-43 percent -- and a bigger female turnout than male, 59-41 percent.

Two key events could influence voters before the primary: Democratic caucuses Saturday in Nevada, and a debate Monday in Myrtle Beach, S.C. Also, all the candidates will flood into the state after Nevada and spend much of next week courting South Carolina voters.

[snip]

As they do, they'll find a state in which Obama has a lead among men, young voters and Democrats.

He also has an edge over Clinton among women, 39-34 percent. He led among women in Iowa, where he won the overall vote, but trailed among women in New Hampshire, where he lost.

His biggest advantage is among those voters who are looking for change, where he leads Clinton by 65-7.

Clinton has an edge among those older than 50. Among those looking for experience she had an overwhelming 81-7 advantage over Obama.

Edwards, who needs to win the state, had few signs of strength.

He appeared squeezed by the white vote -- he had more white support than Obama but less than Clinton -- and frozen out of the black vote -- he had only 2 percent of the African-American support.

Clinton and Obama essentially divided the vote on those most interested in Iraq, the economy and health care, while Edwards lagged among all three groups.

Also, Obama has a slight edge on the favorability numbers (o-67/16; C-62/14; 56/13). Edwards actually has a slight edge when it comes to the firmness of support (O-79; C-78; E-81).

As far as trends are concerned, the last poll from Mason Dixon was takin in early December, according to which Clinton led with 28%, Obama had 25%, and Edwards with 18%.