XPS ????, reinstall Windows 7, product key?

w7 goes dead next month (zero support, MS )

when i give microsoft the product key (what does that mean, ? how are you talking to MS.

but your key is NOT  real Microsoft key at all, it is Dells OEM key for you. and you alone.

your key is not MS nor MS retail full  price key  and are not sold now by MS at all. nor is there support now at MS jan,2020

you failed to use DELL install disk is my guess,  you never told what disks you  have, or install media,?

just upgrade to W10,  get a real OEM key there for $5, end the pain of W7 forever, and the 400+ updates.

end it. and win. but no PC told yet, XPS what?

A valid windows 7 Key will work with OEM System Builder Media.

You buy a DVD and install with the "I don't have a key" option for Home or PRO

You then activate using the Windows 7 COA Key.

https://www.newegg.com/microsoft-windows-10-pro-64-bit-reinstall-recovery-disc-only-no-license-key-included/p/N82E16832350238

There is no point installing 7 as its dead in a few days forever starting in JAN 2020.

This works on most Dell models from 2006 on with AT LEAST Pentium D 900 Series CPU or better.

So XPS 400 from 2006 works.

Not supported does not mean not working.

https://www.youtube.com/watch?v=qa9b0TkTsLM

Here's the info-- https://support.microsoft.com/en-us/help/4057281/windows-7-support-will-end-on-january-14-2020 

If your model cannot be upgraded to win 10, consider buying a new computer. However XPS desktops can upgrade to win 10 even older models. I have 11 yr old xps desktop that runs windows 10 using the MS drivers. It works fine for the grandkids.

https://www.microsoft.com/en-us/software-download/windows10

I was asked to do nothing when i install Windows 7 on my Dall laptop.I was using an installation disc of Windows 7.