why is it you always figure it out after you post on forums for help!
If any one is interested - the ads are added into the wp_options (or wp_X_options if you're using MU)
to import them over, I exported the wp_options table from the blog with the ads already set up and opened it in a text editor. I then looked for the line that contained plugin_advman and copied this line of code to the clipboard.
Switch to the new blog's phpmyadmin and look for the same line in the wp_options table and make a note of the value in the 'option id' field, then drop this entry
in phpmyadmin on the blog i wanted to copy them to, i went back to the wp_options table and hit the sql tab. I pasted in the code from the export and changed the option id to the same as the one i'd just dropped from the table and hit go.. few seconds later all done and my ads are showing up on the 2nd blog
hope that makes sense..