Thank you I will have a go

You can download the ISO from the Digital River links here:

www.howtogeek.com/.../how-to-download-windows-7-8-and-8.1-installation-media-legally

And use the manual install procedure:

www.dell.com/.../EN

I recommend following my instructions as it will give you the Dell OEM system locked preinstallation and save an unnecessary call to Microsoft:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows/a-clean-install-of-windows-7/

Plus it will instruct you in updating Windows 7 Offline, installing drivers in the correct order and give you the means of making a new factory partition with Dell Backup and Recovery.