Ok Greg, theog, I will have a go. One thing though, instead of wiping out the HD, I thought it would be better if I just remove it? No HD, no issues?

My laptop has a dual HDD support (independent, non-RAID), so I will take the W8 disk out and will leave the SSD one. I hope that works.
I cannot believe legacy MBR is not supported. [
EDIT: It is supported, look at the first post of this thread - You need to enable "Launch CSM"] erhaps, ASUS can fix this with BIOS updates?
In relation to the DVD, I have used this DVD before on another laptop. It is fine (I just didn't activate it). It's authentic MS one. I bought it exactly for this purpose which is why I didn't activate it on old laptop. Now, I can't even use it. I will let you all know how I go.
I hope there is a hidden legacy MBR setting somewhere....[
EDIT: Yep, it's called
"Launch CSM" and it is not hidden, it is in the BOOT section]