More exchange 2010
This time an upgrade from exchange 2003... put it this way, it only took a few hours... it was that smooth.... and i actually bother to use the certificate wizard for the first time (all the other installs ive just installed the cert locally and assigned it, havent had to create new ones) - very bloody good.
Still wish the exchange team would put simple things like mailbox sizes back into the UI.... but its a bucketload better than 2007 for simple admin.... and along with DAG's - the product is a winner.
