YEY I now have my site migrated to DNN 4.3.4 from DNN 3.1.1 and here is how it was done.

First backed up my site and Database

Now unzipped the DNN 4.3.4 Install zip file into my root folder and allowed it to overwrite the files.

renamed the web.config file to web.config.resource and renamed the recource.config file to web.config.

Made the changes as per my first post, un-commenting the MSSQL sections  and leaving the express section commented out.

Then changed the .net version to 2 and launched the site. The install went through and upgraded my site for me, once it was done all that remained was to put back any custom container skins etc and all done.

What seemed like a large task at first was quite simple once I read and re-read the docs and forums.

I hope this helps anyone that is looking to do the same as me and thanks to all for the help