I'm trying to make my gVim installation as portable as possible, and in doing so I want to put the _viminfo file in the $VIM directory rather than $HOME. I'm pretty new to hacking vimrc configurations, but here's what I've been trying:

let viminfopath=$VIM."\\_viminfo"
execute "set viminfo='1000,n".escape(viminfopath, ' ')

" Some other portability stuff.
set nobackup
set nowritebackup
if has("win32") || has("win64")
    set directory=$TMP
else
    set directory=~/tmp
end

This doesn't seem to be working, though; does anyone have any tips?

Thanks!