I have been using a plugin called Adman and it does a great job of placing adverts at the top of a post, in the middle of a post or at the end of a post. All you have to do is upload the plugin to your plugin folder, activate it and then add the Adbrite code via the settings page and that is it. It works with 2.7.1
I have explained how you can do this in my blog http://everythingoutthere.izfree.com/2009/02/add-adbrite-or-adsense-to-wordpress/ You need to initialize a counter and put a conditional statement. Check the site as I cannot put the code here.
First you need to parse the HTML and then place the code in the posistion you require with div tag...
the easiest way of doing this is to convert your ad code, Use this>> http://www.everything31.com/2008/05/blogger-ad-code-converter.html <<adbrite, adsense ad code converter, just paste your ad code in text field and click convert, and your code is ready to be paste in your blogger template If you need more help, PM me, Good Day!!!
Right Convert your code here - http://aioupdates.blogspot.com/2010/01/blogger-code-converter.html and after that paste it below the line in Edit html of blogger (Code here for below title & above posts) "<dataost.body/>" (Code here for below posts)
Thank you for you to benefit it in this way I learned where the error does not appear in the Code of Advertising
adbrite ad codes should be parsed before adding it to your blogger template. So search google and find adcode converter and paste the converted codes.