Building pc what about the os?

Just buy and OEM system builders copy from somewhere like Amazon. This basically gets you a sticker with the product code and the install disks. In my opinion the best and legit way to do it. Now that Microsoft actually price their OS at a reasonable price I think it's well worth it because you get piece of mind and support from Microsoft if you need it.

I bought Windows 7 recently to upgrade my ageing windows XP rig and it was £69.99 from amazon for Win7 Home Premium 64bit.

You could of course use Linux if your an elitist and like spending ages making mundane every day things work   it is free...

Also that is a bit of a dig at Linux users but I have used ubuntu in the past and in fairness it was excellent... it's just that I'm a gamer and it was just too limiting.

I would note that, unless Microsoft changed tunes with Windows 8, there is no Microsoft technical support when using OEM System Builder versions of the OS. Generally speaking, as long as you have access to the internet, this isn't an issue.

Unless I have an active Microsoft Technet subscription, I always purchase an OEM System Builder version of Windows with a new system.

-Wolf sends

Thanks WolfShadw you are possibly right there regarding support from Microsoft. I was working under a little bit of an assumption there if I'm honest!