WordPress MU

I've tried but wasn't successful.

The sidebar Categories have a bullet infront of the Title and each category, where do I remove the bullets?

I've tried in style.css but it didn't work for me. Perhaps I messed up somewhere.

It would be more helpful if you provided a link so we can see what's occurring.

http://tackletog.com/blog/jip/

The bullet infront of Categories. That's the default.
Using wp_list_categories

BTW, I tried adding this to my style.css but no change.
li { text-decoration:none;}

use list-style-type:none;

Thanks Ovidiu

While on the topic, there seems to be some padding or margin that's between the bullet and title of the category. How can I remove the margin?

Tried margin: 0; and padding: 0; under li

If I remember my CSS correctly, the padding/margin of an unordered list is on the <ul> tag and not the <li> tag, so try changing the padding/margins there. I know there is a web site out there that lists all the "default" css settings for standard HTML tags, but can't find it at work since I have very limited access.