When I download a contact list theme from adiumxtras.com, it comes up on my desktop as a folder like normal, and when I open it, there are usually two files, and sometimes a read me. The two files are the name of the contact list with a suffix of either .ListTheme or .ListLayout. But when I try to open the files, it says "There is no default application to open the specified document, "blahblahblah.ListTheme (or .ListLayout). This is very frusterating because my current contact list is very ugly and I really want to change it. I am pretty sure this is the only AdiumXtra that doesn't work for me, because I downloaded a message theme, and it applied itself like it should and works perfectly.
Should I remove the fire.AdiumTheme thats currently in there. And the closest match to what you said is the Themes folder, I trust thats what you mean? There is no Contact List folder.
Probably, guess it's changed its name. Up to you if you want to remove what's there already, depends if you want that theme available as an option in Adium or not.
Themes were the old system of applying some contact list and other GUI settings. The new Contact List themes/layouts and other things have superceeded them.