If you are in the market for a jabber server, the only real advice I can give is to skip Wildfire. After a week you'll find interesting system loads ranging from 40 to over 200. That's with one user on a dual Athlon MP 2800+ box with 3GB of RAM. I can only imagine what would happen if two people registered.

I'll probably give ejabberd a try next. It lacks the pretty web interface Wildfire has, but that's hardly my primary concern at this point.