Microsoft has released a tool that allows you to enter your keyword that you are using in your SEO or PPC to see if the keyword is a keyword customers use when in the buying stage. We have put our best and worst keywords through the test and each time the Microsoft Commercial Intention Tool was very accurate. I would suggest checking all your keywords prior to sending your keyword list over to your SEO team or doing PPC.

http://adlab.microsoft.com/Online-Commercial-Intention/Default.aspx