I'll be honest with you, I purchased a computer on Gumtree and it happened to have an illegitimate copy of Windows 7, I upgraded to windows 10 all fine and then a few days ago it popped up saying it was invalid. Well, this was a kick in the teeth as the Microsoft store wanted £180 for a copy. A quick google of "Windows 10 Pro" on Google came up with Software Geeks and I honestly was very skeptical about the prices. A quick Google search came up with some positive reviews and I thought, I might as well try for £22. It was a good gamble as within 30 seconds of the order I had my Windows 10 Pro key and it validated perfectly. I'll definitely be using them again for any future OS's for other computers I may need.