In summary, if you are buying a new PC, it's probably best to buy the OS separately.
I'm liking Win8 thus far, but had I not needed it to run Photoshop/Lightroom I'd have gone for a Linux installation instead. It's not worth the £££.
That said, even though I've paid the exorbitant £££ to activate Windows 8 Pro just for the sake of getting a working system (I've projects to complete!), the end result is still less £££ for the equivalent iMac so I'm not overly upset.
Rusky,
Google-Fu turned up the Pro install media on a public Google Drive so I downloaded and tried that.
Extensive research indicated that the install media for Windows 8 Core (basic)/Pro is the same, and the that UEFI embedded product key should ensure the correct version gets installed.
Not so in my case. I couldn't force the installer to install the Core version. I also found Windows 8 upgrade media and tweaked that into doing an install on an empty hard disk. Same net result.
Some of the OEM versions are "CoreSingleLanguage" or "CoreSingleCountry" so I figured I probably needed one of these - but finding one to match your product key is a needle/haystack affair. There's a few hacks around for editing the installation media to get it working - but it goes beyond my level of trial/error patience.
It seems the Microsoft and OEMs have betweened them thoroughly shafted the consumer with lack of installation media and no ability to create installation media for recovery. The Windows 8 flavour system restores require having the recovery partition intact. If you are converting a system from HDD to SSD or recovering a failed HDD, you need to do your research first and handle with care.