\documentclass[english,10pt]{letter}
\usepackage{invoice}
\usepackage[inline]{fixme}
\newenvironment{narrow}[2]{%
  \begin{list}{}{%
      \setlength{\topsep}{0pt}%
      \setlength{\leftmargin}{#1}%
      \setlength{\rightmargin}{#2}%
      \setlength{\listparindent}{\parindent}%
      \setlength{\itemindent}{\parindent}%
      \setlength{\parsep}{\parskip}}%
  \item[]}{\end{list}}
\renewcommand{\textfraction}{0.15}
\renewcommand{\topfraction}{0.85}
\renewcommand{\bottomfraction}{0.65}
\renewcommand{\floatpagefraction}{0.60}
\newenvironment{enumerate*}%
{\begin{enumerate}%
    \setlength{\topsep}{5pt}%
    \setlength{\itemsep}{0pt}%
    \setlength{\parskip}{5pt}}%
  {\end{enumerate}}
\newsavebox{\sbitemize}
\newenvironment{itemize*}%
{\begin{lrbox}{\sbitemize}\begin{minipage}{9cm}\begin{itemize}%
    \setlength{\topsep}{5pt}%
    \setlength{\itemsep}{0pt}%
    \setlength{\parskip}{5pt}}%
  {\end{itemize}\end{minipage}\end{lrbox}\setlength{\fboxrule}{0.0pt}\fbox{\usebox{\sbitemize}}}
\addtolength{\topmargin}{-1.7in}
\addtolength{\textheight}{3in}

\name{Don Armstrong}
\address{
  Don Armstrong\\
  5045 Kensington Way\\
  Riverside, CA 92507-6044\\
  {\bf don@donarmstrong.com}\\
  714-813-8531}
\newcommand{\CLIENT}{Client Name}
\begin{document}

\begin{letter}{
    \Client\\
    \fixme{Address}\\
    \\
    }

    \opening{\ } Please find the invoice for work performed for
    \CLIENT\ by Don Armstrong on \fixme{Project} from \fixme{FromDate}
    to \fixme{ToDate} below. To pay via check, please make checks
    payable to ``Don Armstrong'' and mail to the address above. If you
    wish to pay via other means, please e-mail {\bf
      don@donarmstrong.com} for further instructions.

  Note: The times below indicate the time spent on each of the
  subdivisions indicated, not necessarily that the task was completed
  in this invoice period.

\begin{narrow}{-4in}{-2in}
  \begin{center}
    \begin{minipage}{\textwidth}
      \begin{invoice}{US}{0}
        \ProjectTitle{}
        \Fee{\begin{itemize*}
          \item 
        \end{itemize*}}{50.00}{1}
      \end{invoice}
    \end{minipage}
  \end{center}
\end{narrow}

\end{letter}

\end{document}