In the past 30 seasons (1979-2008) the team with the best regular season record in MLB has won the World Series 5 times:
1) 2007 Boston Red Sox: 96-66 (their record was tied for the best in MLB with the Cleveland Indians)
2) 1998 New York Yankees: 114-48
3) 1989 Oakland Athletics: 99-63
4) 1986 New York Mets: 108-54
5) 1984 Detroit Tigers: 104-58
The team with the best regular season record to lose was the 1906 Chicago Cubs who went 116-36 and lost the World Series to the Chicago White Sox.
They split the 2010 season's series with three wins each.
2010-11 Celtic
The Astros best regular season record was 102-60 in 1998. They were defeated by the San Diego Padres in the NLDS that season, 3 games to 1. The Astros only World Series appearance was in 2005 where they lost to the Boston Red Sox, 4 games to 0. Their regular season record in 2005 was 89-73.
Through the 2010 regular season, 0-1 in the regular season and 0-1 in the World Series.
The Seattle Mariners is one of two Major League Baseball franchises that have never appeared in a World Series. The Washington Nationals in the other.
114-48 in the 1998 season. They went on to win the World Series that season.
The Jets presently lead the series 45-42-1 in regular-season games. The Dolphins have won the only playoff meeting to date, in the 1982 season.
Occasionally if games get postponed, then there could be a five-game series, but typically, the most games in a regular season series is four. The most commonly occurring is a three-game series.
165 in the regular season (career record was 165-87) and 4 in the World Series.
I don't believe the Royals and Cubs have met in regular season action.
As of July 30th 2014 the series is completely tied at 9-9 regular season and 1-1 post season.