I know this question has been asked a million times before this, but I can't find any suitable answer so please bear with me.
In brief: I want to dual-boot Ubuntu 14.04 and Windows 7 Ultimate. There was a slight hiccup at the fact that I had Ubuntu installed first, but I managed to handle that. I have 450 GBs of space on a partition on my HDD in NTFS (this is the partition where I want to install Windows). My HDD has been GPT since the start and my motherboard (MSI 970 Gaming) definitely supports UEFI+Legacy. So everything is okay on that front, but the windows installer still warned "The selected disk is of GPT partition style."
After asking around on some Ubuntu forums, I was told there is something called IOMMU that has to be enabled, and that its supposed to be available on the 970 chipset, but I couldn't find that option in my BIOS (MSI click BIOS 4). After further research I came to know some motherboard manufacturers choose not to include that option and I chose to go with that explanation (please correct me here if I can't see big red buttons screaming "IOMMU").
I have backed up all my Ubuntu data and formatting the entire disk is an option that can be availed of, but I would prefer not to have it that way. Additonally, I want to actually get Windows 7 to work with GPT rather than just re-formatting the whole drive to MBR and calling it a day. An Ubuntu live USB is also something that can be used if required (I have one at ready).
I don't understand what I'm doing wrong. Please help me out of this spot of bother.