%\begin{table}[h]
\begin{center}
\def\V{\rule{0pt}{2.5ex}}%
\begin{tabular*}{\columnwidth}{lll}
{\bf Programma}&\multicolumn{2}{l}{\bf Tempo impiegato}\\
&Squirrel &Memoria\\
\V%
ImageFX 1.51           &$3' 10''$    &$42''$\\
ImageStudio 2.3        &$3' 09''$    &$1' 34''$\\
GfxLab24               &$2' 50''$    &$1' 48''$\\
\end{tabular*}
\end{center}
%\end{table}