Um...I know the topic hasn't been posted in for a long time, but I am very enthusiastic about chi, so please don't mind my addition.
For what I practice, chi is absolutely essential! I think I've heard from my superiors that we normally study chakra first, but I haven't been taught much of that just yet. Our chi is centered around elements, with each person having his or her own special set based on personality and how the element is reflected in nature. I happen to be of the Ice element, and do you want to know what is scary? After I meditate for just a little while, my finger tips become freezing cold, yet the rest of my body is warm, right up to my palms! I know that chi is a controversial subject, but I fully believe in it. I use it for healing, and I have been lucky enough to see it. Chakra is invisible, but chi has the potential to be seen if it's strong enough within the person. It's different for each person, but my chi is a combination of white rays extending from my fingertips and a strange white afterglow when I move my hands slowly. Now, to clarify, it's not bright and vivid and neon with flashing lights; it's a little bit faint, and you do have to look a little bit close to see it. I have had an unattuned person walk into my room while I was practicing before and ask me what it was. I really thought I was dead meat at that point, but I got off without too many questions...