|Thanks for the reply.|
It is enabled, it's just that Windows thinks it isn't.
I've discovered that if I don't use Windows to configure wireless networks, the red x disappears but then I don't know how to connect it to my network because, while it does now appear to be working, there's no program to find available networks (if that makes sense).
Edit - I don't have the Intel ProSet/Wireless program, I'll get that and give it try. Thanks for the link :-)