Exchange technical resources by HP
HP has been a major Microsoft partner since I remember, probably even more a close partner since the Compaq acquisition. As a curiosity I can tell you that my first Exchange installation ever, version 5.0, was made on a Compaq ProLiant 1600.
HP and Microsoft have worked together to produce some quality Exchange Server documentation. All these technical resources are available through this link.
In the past I have blogged about one of their coolest tools, HP Storage Planning Calculator for Microsoft Exchange Server 2003.
I also had the opportunity to put my hands on one of their storage servers and I wrote 2 articles about the subject:
All with the valuable help of HP's Exchange technical documentation.