Not to worry, I understand real life gets in the way of these things! I'm still here :) You're more than welcome, glad I've been helpful!
Right then....
I've been doing some more research on Windows licensing and yuck, it's confusing... I've spent an hour or two looking over it all, and it still confuses me... But I've been doing some research, and it's all getting a bit confusing, but here is what I have found. If you purchase Windows 8.1, you won't get the option to keep your programs when you upgrade, only your files. If you purchase Windows 8 then you can keep programs, settings and files, and then upgrade to Windows 8.1 once you've installed Windows. I've just tested this on a virtual machine, and can confirm this.
However, you have a copy of Windows 7
Enterprise. That is a problem because it renders the above
invalid. Microsoft creates the enterprise versions for businesses, and not generally consumers. This means they expect the install to be supported by an IT infrastructure and managed by an IT team. They do not expect it to be upgraded to a newer version of Windows, because that's not how it would be done in an enterprise environment. It's supposed to be a clean install. So.... unfortunately you're going to have to clean install Windows 8.
I sincerely apologise for not telling you that sooner however I only just realised that myself.
Both the OEM and full version are the same, but the OEM copy will only allow a clean install regardless of the version of Windows installed previously. If you don't want to purchase a physical copy, you can download it online. In Microsoft's tutorial here:
Upgrading to Windows 8.1 from Windows 7 - Windows Help, they link to the Windows 8.1 Upgrade Assistant. If you download and run that, it will check your system for compatibility, and then offer you the option to buy Windows 8.1 there and then.
Sorry about this, there's nothing I can do about it I'm afraid...
Stephen