Style guides disagree on which words to capitalize in a title.
Here is one that is a variation of the Chicago Manual of Style rules:

1. Always capitalize the first and the last word.
2. Capitalize all nouns, pronouns, adjectives, verbs, adverbs, and subordinate conjunctions (“as”, “because”, “although”).
3. Lowercase all articles, coordinate conjunctions (“and”, “or”, “nor”), and prepositions (under five characters).
4. Lowercase the “to” in an infinitive.

The U.S. Government Printing Office Style Manual offers one easy style:
“Capitalize all words in titles of publications and documents, except a, an, the, at, by, for, in, of, on, to, up, and, as, but, it, or, and nor.”
[from Writers.com]

Here are some sites for further exploration:
Writer’s Block
eHow
AdminSecret (cheat sheet)
Writers.com