Whether you've already early voted or are waiting to cast your ballot until Tuesday, the process your vote goes through is the same. When you cast your vote for America's next President, you're actually voting for 34 Texans who make up the electoral college. These representatives will then, hopefully, represent you well and cast their votes for your choice candidate.
If John McCain receives the majority of the popular vote in Texas, all 34 Republican electoral college members will cast their votes, and the Democrat members don't vote at all. The exact opposite will happen if Barack Obama carries Texas.