Texas is the most un-primary of primaries there is.
For one thing, there aren't any delegates awarded to the winner of the state -- no statewide bonus delegates, nothing. For another, a third of the delegates will be chosen through a complicated caucus system.
And instead of proportional allocation by congressional district, the rest of the delegates will be proportionally allocated by state senate districts. George W. Bush's '04 performance really changes the math. That's because the number of delegates allocated in those districts are based on how well (or poorly) John Kerry did, as well as the performance of the last Democratic gubernatorial candidate (who himself had votes taken away by a liberal third party challenger.)
The delegate-rich districts are the most heavily liberal state senate districts. According to this calculation, they're in Austin and in two of the most concentrated African American parts of the state. Advantage: Obama.
Clinton will get plenty of support from Latino voters, but they tend to be more spread out and thus will see their votes somewhat diluted in the 31 separate primaries. In order to "win" -- both enough delegates and statewide, you need to organize what amounts to caucus-like campaigns in each of these districts.
The white vote in Texas will probably split, with Obama taking men and Clinton taking women. Though Latinos make up a slightly larger share of the electorate than African Americans, they tend to vote in lower proportions.
The process has two steps. First, folks vote. 126 delegates will be accorded proportionally via state senate district. Then, when polls close, they caucus in more than 1,000 precincts.
At the caucus, attendees chose the identity of the delegate and the presidential candidate that the delegate is supposed to represent. These delegates are sent to a "senatorial convention" a few weeks later, during which the final math is worked out and the actual delegate slate for the convention is chosen.
67 delegates will be chosen this way.
Suffice it to say: whatever you call Texas's system -- a hybrid, a primacaucus, whatever -- do not assume that, because it's a big state and the media calls it a primary, the math favors Hillary Clinton.