This bundle makes vim display line-numbers when you are editing files (without making them appear in panes like your NERDTree pain). It also enables the ruler at the bottom of the pane to show your current column.
If you want an easy install, use Tim Pope's pathogen.vim.
cd ~/.vim/bundle
git clone git://github.com/Elzair/vim-line-numbers.git
If you do not want to install pathogen, you can copy the ftplugin directory into your ~/.vim.