You can download Windows 10 from Microsoft as an ISO, and then download the drivers from Dell. www.microsoft.com/.../windows10
Hello everyone,  My old hard drive had some issues and unfortunately died. I'm in the process of going through data recovery because I wasn't able to back up all of the files.  However, I'm also getting a new hard drive (SSD this time) and I need a Windows installation file in order to get Windows back on it. I have an Alienware 17. I understand that the product key is in the BIOS itself, but I need to get a Windows 10 installation file. I checked the Drivers and Downloads section of the Support Page but it doesn't seem to be there.   Lastly, when I do get it, all I will need to do is turn off Secure Boot, right?   Thanks for your time! 
Getting Windows on My New Hard Drive