I've just switched over to houdini 5.5 and of course textures and materials are now defunct. I'm trying to figure out how to use an existing image as a bump map as well as a texture. (Much like the texture and bumpmap texture sops in previous versions worked) How do I go about doing this?

If you are you are rendering using Micropolygons try using a Vex Displacement Map shader. They render fast and look really nice.