Wordpress post or page question

I have been using wordpress for some time, but never checked my results in google that much. Silly me. Now I have been building some adsense sites and noticed something. I always make my first entry a post. Then I usually make the rest of my content pages.

When I checked a few of my sites today in google with site:domainname I found that it indexes the post as the domain name, and also as the name of the post.

So if my domain name is nicekitchenlamp.com and I make a post, "how to find a nice kitchen lamp" it will show both.

When you go to site:nicekitchenlamp.com it will show

nicekitchenlamp.com
nicekitchenlamp.com/how-to-find-a-nice-kitchen-lamp

I can't put the www because this forum will turn them into links, but they are both clickable, and both pages will show up, With The Same Content, because they are in-fact the same page. I can't believe that is good.

Should I start making my first entry a page, and then make the rest posts?

Any suggestions would be appreciated.

Thanks Glenn