those wondering how to reformat and reinstall windows for dell laptops... even if they dont come with recovery DVD... look inside the laptop for a file named "factory.wim"

this is your factory setting original windows image.. all the serial info built inside already apparently such that when you reinstall this .wim image.. you do not need to re-enter the windos serial number..

so find this factory.wim and make a backup copy somewhere... in your backup external HDD or your DVD or your thumbdrive... whenever you need to reformat.. use this image again...

how to restore factory.wim... that's a whole different story.. it could be tricky.. just be sure that the image is x86 or x64.. and use the image restrore software corresponding to it..