Nevermind now I have found this out:
Outlooks 2007 has switched to word for its rendering engine, where as it used to be IE.
This means it no longer supports:
position and float CSS;
We now have to work around these unsupported features and re-deisgn any HTML formats yo 'used' to e-mail since it's estimated that already 40-45% of outlook users are already on Outlook 2007
the link for the article: (please don't move admini- there's too much content to paste ?)
Hope this is a useful piece of advice for anyone attempting mail-marketing!