Yes, Googles' Keyword Tool is a must have, must use, can't live without tool.
Even though it is a free tool you need it to determine the amount of traffic you can count on for certain keywords.
But once you find the keywords you want to build your campaign around you should use WordTracker as well.
Google will give you the keywords that are making money for Google. That means these keyword receive a lot of traffic and Google wants you to bid on them.
Word Tracker will break down these keywords into the long tail keywords and that is where 94% of the traffic for most websites comes from.
Building your website or articles around these long tail keywords will improve your chances of being seen quickly.
Word Tracker has an affiliate program which I participate in.
If you click the link below and become a paying customer of Word Tracker I will receive compensation.
They have a 7 day test drive that will show you all that you are missing with only using Google. BUt it all Starts with Google.