Okay, I'm almost settled on my plan of action, I just need to know one thing.
If I use an upgrade edition for Windows 8 on my OEM copy of Win7 will I then be able to activate said Win8 on a different computer in the future, say in the event of me needing to re-install Windows due to a harddrive failure? Because, needless to say, I will never be able to access that OEM copy of Win7 ever again as it's a Dell OEM and their machines are shipped with backup partitions on the harddrive which allow you to reinstall Windows but they do not come with installation DVD's for Windows.
This is an important question and I need an answer, without one the only thing I can do is drop £120 on a retail copy of Win7 blindly and hope that it was the smartest move