"Windows 8 is really pissing me off - apparently flaws in design compatibility make it very difficult to uninstall Windows 8 and then replace it with Windows 7 and also breaches a lot of warranties on systems issued with Windows 8."
Yeah had to do that for someone a week or so back. Basically you need to switch off uefi in the bios, delete all the partitions from the hard drive (or just use a new hard drive),reformat the hard drive then you should be good to go. You'll still have your hardware warranty but not your software warranty. But lets face it, if you're going to that much hassle better to buy the parts and build your own PC (not for laptops of course.)
"Is it worthwhile running a virtual Windows 7 over the top of Windows 8 ??"
Depends on how much overhead you have I guess, if your hardware can handle it without a speed hit then why not?