In 'webmasterbucket.css' there are 'td.row1' and 'td.row2' elements with 'background-color' attributes. Setting these to different values will cause the posts to have alternating background colors. The old messageboard used values #f5f5dc and #ffffcc, if you are interested in a
homey feeling. The 'background-color' attribute under 'td.row3Right, td.spaceRow' contains the value for the spacer between posts. I assume this information applies to the other themes.
And, is it a good idea to have the archive forums open? It seems daunting to pay attention to so many forums, even with a graphic for new posts. General discussion around here tends to fall into those categories anyway.