On my 12.04 with default configuration vi is a symlink to vim.basic, just as vim, so 't is the same program.
Per user configuration of vi(m) is in .vimrc in the home directory, system wide configuration in /etc/vim/vimrc or /etc/vim/vim.tiny. Something could be wrong here.
Which colours are used by vim depends on whether you have a dark or a light background in your terminal. Vim typically guesses the background (don't ask me how) and then selects either light or dark letters. The problem might be that when you use sudo vim has trouble guessing the background. It can be set manually with