I hate to harp on UBB versus vBulletin, but I move around to various browsers all the time, and UBB doesn't keep track of what I've read and haven't worth a darn.
Follow that link and read what they have to say about UBB. It's true. It's nasty.
vBulletin allows you to import UBB message. Whaddya say...?
Solo-1 Record holder, Mosport DDT