Vim: auto-install for Vundle

My setup (especially my config files in my $HOME) are synced across many machines using a dedicated git repository. Up until now, I've used TPlugin and a bunch of subdirectories in ~/.vim/bundle to handle it. Unfortunately, this never really worked well.

So, I switched to Vundle, which is AWESOME. Now, how do I install vundle on all my machines? Some of them are only used rarely and it's quite possible that I'll forget where to get vundle from in that moment. And then, all my plugins would be missing (apart form the error message of not finding vundle itself)

This is what I hacked up in my .vimrc to fix this:

" If vundle is not installed, do it first
if (!isdirectory(expand("$HOME/.vim/bundle/vundle")))
    call system(expand("mkdir -p $HOME/.vim/bundle"))
    call system(expand("git clone $HOME/.vim/bundle/vundle"))
    echoerr 'Vundle was freshly installed. You should run :BundleInstall'

set rtp+=~/.vim/bundle/vundle/
call vundle#rc()

" let Vundle manage Vundle
Bundle 'gmarik/vundle'

" Rest of my bundles follows below