Izzmo is right on the money. IE6 and earlier versions were not standards compliant. They did their own thing the way they thought it should be done rather than use the standards put out that most other browsers abided by.
Now Microsoft has figured out that being standards compliant would be a good thing. You did the same thing that I did and probably most of the rest of us that learned on our own did. Until recently 97+ % of the browsers out there were IE. You design your first sites to work in IE. If your site wasn't a computer related site, almost everyone that got to your site saw it perfectly.
Things are changing now and more people are using other browsers. IE still dominates (no matter how much lots of techies would like it to be different) and Microsoft has gotten with the standards finally.
Browser history lesson over

Stop lecture mode....
Shutdown....