As far as I'm aware, most new systems don't come with Microsoft Word or Microsoft Office. You have to purchase the software separately, which is a huge bummer, I know.
To answer the question specifically: No, Vista does not include Microsoft Word or Office as part of the pre-installed software.
RL: I would guess it's because "notepad" is an actual word, whereas "WordPad" hasn't achieved that status; it's just a compound masquerading as a word to be a clever program name.
Sara