The UEFI thing screwed my head a bit while trying to install Ubuntu 12.10 in Dell 7520, I made separate partition in Windows 8, installed Ubuntu via liveUSB it went well, but Ubuntu didn't load. So, I hit the Ubuntu install again, it asked me to erase previous Ubuntu, I said yes, now the Ubuntu 12.10 works perfectly.
I used boot-repair to repair the GRUB as suggested in some answers here, and when I reboot, there was no option for windows 8. I booted to Ubuntu to check the Ubuntu have used whole 1 TB (total space). That means I deleted windows ? If so, any way to get the setup back? I don't have repair disk, nor DVD. Win8 came pre-installed.
For the ones who are looking for such solutions, there is NO WAY to get it back, at-least in my kind of situation. I again installed the windows from DVD (I got it from Dell Customer Center, and while purchasing this Laptop I had one month of premium support, which made things easier).
I installed windows8 with DVD and not selecting UEFI and I used G-Parted from LiveUSB to create partitions, Hence, installed Ubuntu 12.10 in other partition via LiveUSB.