I think it all comes down to whether you want the hassle of needing to have your iPod available in order to hear stored music on your stereo - Airport Express does away with all that, and if you add
airfoil, you can stream
any audio from your computer to your hifi (BBC Radio, for example). Unless you have an iPod Touch or iPhone, though, there's no remote control - you have to manage it from the computer.
Note however that after initial favourable impressions, I have found audio quality of the AE to be lacking compared to CD, even with lossless and a better cable - hence my search for a DAC. You may find it worth spending the extra and getting a squeezebox.
But instead it just kept on raining
My useful posts: