Spaces after periods

I never thought I would have to talk about the number of spaces after periods in a workshop setting. I've just had it ingrained in my brain for so many years now (since I first started learning MLA) that you put one space after periods, not two. It's also what we teach people in typing and word procesessing classes. It's the new way. Putting two spaces after a period is very old school. (I will admit, until sometime mid-college, I was also convinced that you should put two spaces after a period, until I found out that rule was archaic.)

Here is an explanation from http://www.writing911.com/writing/good-writing-tips/punctuation/one-space-after-a-period-or-two-weve-got-the-answer.html :

Today, using just one space is correct. In BC times (Before Computers), printing presses and typewriters used letters that were all the same width. To help readers see that a new sentence was starting, we inserted two spaces. Today, computers compensate for the varying widths of letters. An "m" no longer takes up the same amount of space as an "i" does. Thanks to these proportional fonts, we no longer need that extra space.

Even the Chicago Manual of Style says that one space is correct. But it seems like everyone still has their own opinion about this topic. I'd like to hear what you think.