When you resize the disk in the Disk Management option of Windows 8, it does not return you back more than about 49-60% of the space it actually uses. This is because, there are swap files, hibernation files and others stored elsewhere on the Windows 8 OS partition.
To actually reduce the size to more realistic size, you need to follow the instructions to shrink a windows 8 partition at this link http://ubuntuforums.org/showthread.php?t=2087466. These instructions will also help if you want to install Fedora 18. Scroll right to the bottom and the instructions are there. Just follow the instructions. Once done, you can follow the same instructions in reverse order to re-enable hibernation, swap and so on.
Many of us who do not use Windows at all, need to get space to install our Linux distribution. This was very useful and one great way to reclaim space eaten by the OEM installation of Windows on the Lenovo Z580 laptop. Now I will install Ubuntu 12.04.2 on the free space. As it is I do not use Windows and if the laptop came with Windows 8, better to have a dual boot with Ubuntu.