I have just recently had to deal with .ico files - creating, getting images from, etc.
After a brief google of available programs, I settled on trying out two: "icofx 3" and "RealWorld Icon Editor". The former is not free, but can be used for a limited "trial period" for free. The latter is free.
My experience with "icofx 3" was not good: I could not seem to extract images from an .ico file easily. I could not find a way to put text into and icon. It seemed to have some bugs in some of its features (e.g. "replacing color" feature did not seem to work.) It may be that I simply did not get familiar enough with it - perhaps those features are there. But if I cannot find them without extra effort, it's not well designed in any case.
My experience with "RealWorld Icon Editor" was excellent. Trivial to install and use, powerful. It easily performed all the functions I mentioned that I could not get "icofx 3" to do. In particular, it will do exactly what you require: you can open an .ico file and view and extract the images. You can find it here: http://www.rw-designer.com/3D_icon_editor.php