maybe i can help clarify a little. I spend most of the day working with google and their serps. there's a great forum at webmasterworld.com if any of you want to learn more.
google does use meta tags, but only in the description and even then, if you're listed in dmoz then that description trumps all. incoming links are what you need to work on, from sites that are like your site themewise and with keywords in the anchor text.
i highly advise against signing guestbooks, google knows about this and it won't help you at all...may even get you banned PR0. good luck