Your Microsoft Office 2007 won't be backed up on the factory image. You should have got a Microsoft Product Identity card with your system which contains your 25 digit product key. You can use this to download an installer from Microsoft and for product activation. For more information including the download link see my wiki Download Microsoft Office. If you do not have your MPI card then run Belarc Advisor on your old installation. This utility will tell you your Microsoft Office 2007 product key. For optimal performance follow my Windows Reinstallation Guide/A Clean Install of Windows 7.
I have an Alienware m15x that I bought from Dell in 2009. I customized my order when I bought it so it came with Microsoft Office pre-installed. Its been getting sluggish and I got hijacked by some adware virus due to my carelessness so rather than figure out how to get rid of it and clean my system I've decided to start fresh and re-install Windows 7. Is Office backed up in my restore partition so if I restore it, Office will be re-installed too?
Re-install Windows 7 and keep Microsoft Office 2007