Wow Roster as a complete module?
That would have to be made a component then.. instead of a module.. and it would be nearly impossible.. or.. impossible in the way that the dev team would need to maintain two versions.. (and when other users saw this.. they'd want it aswell for their cms... so it would be XX versions eventually)
Wrapping, and making it look good in joomla is two different things..
Check my site out..
Joomla wrapped in IE:
http://www.fc-guild.org/images/joomla_roster_IE.JPG
Joomla wrapped in FF:
http://www.fc-guild.org/images/joomla_roster_FF.JPG
What i've done.. is to take out the bits and pieces we need..(see pic below) instead of just wrapping the entire roster into the site..
This works great for us.. and there's no visible change from IE to FF..
Common problems could be..
Not changing the default options on a wrapped link, as in not changing the size of the page etc..
try fiddling with the settings like shown below
CSS leaks from roster into joomla's templates..
This can be caused by a number of things.. but usually.. you've chosen a poorly written joomla template..
Try with another.. or write your own template! :-O
I hope it helps a bit..
Also, i guess you've looked through the joomla guide i've written (can be found in this forum)