If you are using the Dell Windows 7 Home Premium Reinstallation DVD it will automatically apply Dell OEM SLP activation. In short a product key is input from the DVD and activates if and only if the BIOS is validated by Dell to run Windows 7. You therefore do not need the 25 digit key on the COA. If you want to know the code then look under the battery. See here for more details: [URL]
Hi, My laptop (Dell Inspiron 1564 - Windows 7 Home Premium) slowed down a few days ago and I decided to restore the system to Dell Factory Image. The process started but stopped more than halfway and gave the following message, "Failed to apply Image". I restarted the system but it would now not boot up, not even in safe mode! Perhaps, during the restore process few essential Windows files have been erased. I want to restore the Dell Factory Image and cannot re-install Windows since I have lost the product key of my original Windows 7 installation DVD provided by Dell at the time of laptop purchase. Your help / advice is solicited and would be much appreciated. Thanks. P.S. System's Recovery Partition is intact and has factory.wim and other related directories / files intact.  
Problems with Dell Factory Image Restore - Dell Inspiron 1564 - Windows 7 Home 
Premium