I tried many different CSS hacks suggested in the WordPress forums, but finally tried a suggestion listed here.
There's no need to visit the above link.
The answer is simple.
In your widget remove the <ul> & </ul> tags. Leave the <li></li> tags. Save your widget. Go to the front end of your website, refresh the browser window, and, viola! you should have a bullet list in your widget.
Hope this can save a few people some time and frustration.