Geek help LaTeX quick!

[one_to_tango]

Right guys,

The only one of my friends who'll know anything about LaTeX is
aidansean , so for once I'll make this open to the web.

I need to make a small table, where each column is aligned around a certain element. In the first column, it's the letter z, in the second column a full stop, the third column a plus-minus symbol, and columns four and five and six and seven follow the formatting of two and three.

That works pretty much fine. What I need to do now is to add as a top row a text entry for the first column, a text entry spanning columns two and three, a text entry spanning columns four and five, and a text entry spanning columns six and seven, and these entries have to be horizontally centered within their cell. I think that I can do this via the multicol environment but I'm not sure. What I've got for part that isn't this top bit follows at the end of this.

All help gratefully received! :)

\begin{figure}
\begin{center}
\begin{tabular}{|r@{$<$}l|r@{.}l r@{$\pm$}l|r@{.}l r@{$\pm$}l|r@{.}l r@{$\pm$}l|}
\hline
-150 & 150 & 3&36$\times 10^{-2}$ & & 4.19 & 6&82$\times 10^{-1}$& & 5.42$\times 10$ & 5&22$\times 10$ & & 3.90$\times 10$ \\
\hline
150 & 0 & 3&20$\times 10^{-2}$ & & 7.73$\times 10^{-2}$ & -9&12 & & 2.66$\times 10^2$ & 4&75$\times 10$ & & 1.78$\times 10^2$ \\
\hline
0 & 150 & 3&21$\times 10^{-2}$ & & 9.01$\times 10^{-2}$ & 4&79 & & 3.51$\times 10^2$ & 5&10$\times 10$ & & 1.66$\times 10^2$ \\
\hline
\end{tabular}
\end{center}
\label{tab:z0}
\caption{Table of Gaussian fitting parameters for the curves on figure \ref{fig:z0}}
\end{figure}