I like the default skin, but the avatars being as big as they are stretch the postbit message area too much with short posts. Although, when there are big posts, the larger avatar looks cool.
The 'darker' style makes the text difficult to read. You may want to go with a lighter shade of gray on that one or a different color on the text.
If it was my site, I would go with a sidebar (for ads and/or latest posts, etc) to cut down on the width of the forum home. And, it would also help to make the messages look longer and it would help with the avatar piece as well
Not a bad start overall. Keep up the good work! :up: