Will this for for a OS

[John3028]

If I download an existing Windows 7 onto a flashdrive from an old laptop, can I use that version of Windows to download onto a custom built PC and just buy a product key from online? Thanks

 

[Luminary]

Why not save yourself the trouble and buy a new Key + Installer Disk? It should only take a few days to ship to your residence if you order it online, or go out and buy it from a store. Either way, same result, same cost.

 

[Dark Lord of Tech]

Just a product key bought online , is not legit and will eventually be blacklisted.

 

[USAFRet]

If I download an existing Windows 7 onto a flashdrive from an old laptop, can I use that version of Windows to download onto a custom built PC and just buy a product key from online? Thanks

No. This fails on multiple levels.
You need to buy a valid, legal OS for your new PC.

The OS is just as much a part of a new system as is the RAM/CPU/GPU/PSU/etc. Are you trying to cheap out on those? Hopefully not.

The license key is what actually costs. Given a valid, legal license, you can download the relevant install ISO direct from Microsoft, for free.

 

[USAFRet]

Anywhere you find online that sells 'just the product key' is not valid.

 

[John3028]

How should I go about getting an Operating system if I don't have an optical drive, thanks

 

[Luminary]

Windows 10 Home edition USB (installer + key):

http://www.newegg.com/Product/Product.aspx?Item=N82E16832588528&cm_re=windows_10-_-32-588-528-_-Product

 

[Dark Lord of Tech]

http://pcsupport.about.com/od/windows-8/a/install-windows-8-usb.htm

 

[USAFRet]

How should I go about getting an Operating system if I don't have an optical drive, thanks

Windows 10, direct on a USB.
http://www.newegg.com/Product/Product.aspx?Item=N82E16832588528

Or, if you're buying Win 7 or 8.1, you can create a USB install from the DVD they send you.