OK. so I got around to building the UEFI bootable Win 7 install DVD, as per mulderlr's post. What a mission. I couldn't use the DVD I had - it didn't have \efi\microsoft\boot\efisys.bin file on it and the oscdimg of that failed. So I busted out the ISO I downloaded (officially) from Microsoft and used oscdimg on that - success. I now I have a bootable UEFI Win 7 install DVD, and the machine will boot in UEFI mode from it. Bad news: it does exactly same thing is the bootable UEFI USB stick I made and hangs at the Windows starting splash screen. So something is wrong with the ISO I got from MS. Going to try another ISO now.
Sigh.
So dicko, how do I create a UEFI bootable Linux DVD or USB with dd or gdisk on it? Sorry Linux really isn't my forte. I just need to be able to get into this machine and kill GPT on the SSD (or at least that's what I think is the correct course of action here).
Thanks for all the help guys. Really appreciate it.