The Office providing with your Dell system should have been OEM. You should be able to download the OEM version from Microsoft here: [URL] If your Office 2007 was from a retail purchase get the installer from here: [URL]  I don't think the keys for the OEM and retail product for Office 2007 are interchangeable.    
Hello there. I have a computer running windows XP and have just factory reset the operating system. I had Microsoft office 2007 install before the reset . How ever i have lost the install CD for this and would like to install this program again. I got my Product key with me still but when I go to download the program off Microsoft website is says it can not recognise my product key. Please can I have some help!
Lost Software