<p>OK, right now the rankings mean very little. They're voted on by sports writers and by all college coaches. There are also a couple rankings that are purely mathematical formulas figured out by computers, but those come out later in the season. For at least the first few weeks, rankings mean little because they are influenced by hype and speculation. </p>
<p>Texas dropped because they lost they're star QB from last year, Vince Young, to the NFL. At the same time, #1 Ohio State has a lot of returning starters at skill positions and #2 Notre Dame benefited from the media's love crush on them. I'm really not biased, because I despise Ohio State and would love to go to Notre Dame, but sadly that's the truth. </p>
<p>And that's exactly why pre-season rankings mean nothing. They haven't played a game yet and Texas gets bumped 3 spots. It's based entirely on speculation. </p>
<p>As for conferences, they are basicaly divisions broken up by regions and relative prestige of the school. There are six big-name conferences (called BCS conferencs, since they winner of these conferences get automatic bids to BCS Bowls): Big Ten (midwest), ACC (Atlantic Coast), Big East (northeast and mid-Atlantic), Big 12 (south-central US, Texas, Oklahoma, Nebraska, etc), Pac-10 (west coast), and SEC (south eastern conference). </p>
<p>There are also numerous lesser conferences in Division 1 football, which are also broken up geographicaly but contain less prestigious and for the most part less talented teams. </p>
<p>For the first few weeks, most games are inter-conference. For the most part, this means the big-time teams beating up on teams from lesser conferences (Michigan vs. Vanderbilt, Texas vs. North Texas, Ohio State vs. Northern Illinois, etc.). These are essentially warm-up games for conference play. There are of course a few exceptions like Notre Dame vs. Georgia Tech that was just on tonight, and Ohio State vs. Texas in a few weeks. </p>
<p>The BCS is the Bowl Championship Series. Basicaly it includes five bowl games at the end of the year, by far the biggest bowl games: Rose, Orange, Sugar, Fiesta, and National Championship game. The #1 and #2 teams in the final BCS rankings play in the national championship game. The other 4 have various conference tie-ins for teams who win their respected conference. For example, traditionaly the Rose Bowl is between the Pac-10 champ and Big Ten champ. These are mearly guidelines, and really the bowls pick which team will bring in the most fans and money. </p>
<p>Hope this helps. Let me know if you have any other questions.</p>