I've been strugling with this topic the whole afternoon...
If I want to change the colorscheme of gvim, it's ok (here with the donbass.vim):

but the same under vim, and the colors are not exact at all:

the content of my vimrc, well it's on the screenshots :D
I'm running Windows 7 and vim 7.4, but I also tried with Windows 8 without success...
Any idea what's wrong? Thank you!
so obviously, even if I set t_Co=256 in my vimrc, it doesn't work...
