Larry Litmanen :
So my question is do i simply copy Windows file from any Windows desktop and just later enter the serial number that came with HP?
No, it doesn't work like that.
1. There is no "Windows file"
2. If you're buying a prebuilt HP PC, with a preinstalled OS, you have a couple off limited choices:
Create the Factory Restore DVD set.
Use that to create an ISO file
Use this:
Windows USB/DVD Download Tool to create a USB install of that. Maybe.
Or:
Buy the SSD, and do a cloning operation from the original drive to the new drive. Many SSD's include an application for that specifically.
This requires that the new SSD be larger than the existing used space on the original drive.