Two" or "Too" or "To"

Two is used when expressing the number 2. Example: "I bought two apples at the store.

Too can be used when adding another thought to an idea (similar to adding the word "also"). Example: "I bought some oranges too."

Too may also be used when something is used in excess. Example: "You bought too many apples!"

To should be used in a sentence that provides more information about the action. Example: "I will go back to the store."

Article from http://www.aboutschool.com/6english.htm (December 28th 2007)