Forget what they told you in class - go look at their websites and see what they are actually doing!

As fas as this OOP, I can tell you from experience that if I put more than a few words on an ALT or TITLE tag for an image, Google lowers my rankings, but MSN raises them! Go figure.

It seems like from Googles point of view, the ALT text should say what the picture is, whereas in MSN they prefer a keyword rich pseudo-description (i.e. keyword stuffed); alas, MSN will eventually catch up with their algorithms. . .