Yes, everything you’ve listed can generate and manipulate normal maps. They can, and probably should be, combined as well. It’s rare that a single tool can complete the entire job.
- Blender itself? I have the latest version, and prefer to use Cycles Render
Blender is a competent normal map generation tool. There are many interesting node setups and strategies for generating excellent maps and combining them. Just searching BA will yield informative existing discussions on the topic. Youtube is also awash in comprehensive tutorials on using Blender to create normal maps.
- Gimp. I have the latest version, and I have heard about InsaneBump, but I have not been able to install the plugin or
even find it online.
I don’t use Gimp, so I really have no experience generating normals with it, but a quick google search turned these up  
- Photoshop. But I only have version CS5, and I can’t upgrade because that’s on my old mac system which won’t support
Here’s the Nvidia filter for photoshop. It is supported by CS5. There are also PS actions which combine normal maps as well. Google is your friend if you’re looking for those.
Follow tutorials and keep asking more questions. Good luck!