In many cases majority wins, so chances are that many are already switching their site designs to benefit 1024x768. However one thing is for sure, when I use 800x600 monitors at school and so on, getting a horizontal scroll bar makes me mad. The main reason would be that I often have to resort to using the arrow keys, because I'm too lazy to use the mouse pointer.

So like Sami says, 20% is still a lot, and I don't think you should 'not care' about those users.

(oh yeah and BTW William I share the same problems as you in spelling, I wish FireFox could have the squiggly lines like safari...)