So, my adventures in OpenGL continue. Managed to get live SDL surfaces mapped onto a cube, although this took longer than I thought. Mainly because I was being thick, and not converting the surface to the correct pixel format prior to binding the texture. In the end I had to google the web to find out how to do it properly, and found some nice example conversion code which was OS and free for use, so I changed that about to suit my needs and everything fell into place...
Yet another example of why Open Source is good. You can learn from it!
The new code is up on my website for anyone that's interested. I have to say, texture mapping a cube with a plasma effect looks pretty cool :)