[Lynne]

There is a hack called Chief First Post and it gives a different postbit to the first post in a thread (like here). That one allows the user to pick it, but you can easily modify it to not allow the user to pick it and just have you, the admin, define it. The hack comes with a couple of added postbit templates. You can play with one of those and see if you can get the look you want. You can also look at the source code of a page that you like and use the same CSS that is used and the same html and achieve an exact look if you wanted.