One thing that hasn't been emphasized enough in this thread is the beneficial effect of TeX for the scientific community, in particular the mathematical, physical, and chemical sciences. TeX has made it possible to easily&freely prepare and distribute manuscripts. There even is a preprint server (www.arxiv.org) that accepts mostly TeX, giving worldwide access to many papers that would after their publication only be available through expensive journals. I don't know whether anybody has ever estimated the costs that all these benefits would have if one was using alternatives to TeX. It must be in the billions of dollars. Besides the ability of TeX to typeset formulas and its costs, it is its level of standardization that makes it so useful for scientists: TeX is an extremely well-defined system. My 15 year old TeX files still `TeX', despite changing computers and operating systems multiple times. The only drawback for the scientific community is that there is no easy way to parse TeX into Mathematics, i.e. make the formulas one can typeset intelligible to a computer algebra system. This is of course possible now with MathML. Matthias