\includinggraphics problem

[shanks59]

Very new user (I'm sure it's very obvious)

I've had no problems to date, but have been trying all night to include  a .ps/.eps image in a file.

Here is my .tex file:

\documentclass{article}
\usepackage{graphicx}
\begin{document}
        \includegraphics{switching.eps}
\end{document}

I keep getting a single error message, typically the following:

! Latex error: Unknown graphics extension: .eps.

Any help would be very much appreciated.