By default Excel will display 3 sheet tabs when you open a workbook. You can then add or delete tabs as needed. Some users never use all three tabs while others use more then 3.
Well you can modify how many tabs open by default.
In 2007 From the Office Button select Excel Options
Select the Popular tab and change the “include this many sheets” number.
You can also change the default font and font size from the popular tab.