Cut and paste text from MS Word into posts or should you use a text editor?

I read in the codex that you should only edit wordpress files using a text editor and not word processing programs like MS Word because the formatting will be different. I’m not sure if this is referring to text from posts that I want to add, or if it just means editing php, CSS and HTML files. I have been writing all my posts using MS word and I have quite a bit of material built up, but I want to be able to just cut and paste them into my posts. Is this okay to do or do I need a text editor? I would hate to have to retype them all again into a text editor first. Can someone please explain.