I haven't ran across any. About the only thing I tell mention is that OL98
is 7+ years and isn't going to expose the benefits/features that Exchange
2003 brings to the table. (e.g. site might not be able to achieve a high
user to server ratio like you can with OL2003. Doesn't expose the Junk
Email Filtering so 1 can set safe sender/recipients, rpc over https is out,
..etc)