I’ve been working with the HP Proliant Microserver. This little unit makes an excellent cost effective server for SBS 2011 Essentials, or Windows Home Server 2011. The unit is inexpensive, and can handle up to 4 plug in Hard Drives. In fact, it also make an excellent NAS device or backup server when running Windows Storage Server 2008 R2 Essentials.
The full information for this unit can be found here – http://h10010.www1.hp.com/wwpc/au/en/sm/WF25a/15351-15351-4237916-4237917-4237917-4248009.html
For SBS2011 Essentials, go with the maximum 8GB RAM, 2 x mirrored 1TB, and additional drives to suit use.
For Windows Home Server 2011, go with 4GB RAM, and as many drives as you need, preferably with a mirrored OS and main data volume.
Always get the UR482E – 3 year Next Business Day Carepack warranty, as this is reasonably inexpensive, and quite worthwhile in protecting your investment.I would also strongly recommend installing the HP Proliant Microserver Remote Access Card ( 615095-B21) – http://h30094.www3.hp.com/product.asp?sku=10265812&mfg_part=615095%2DB21&pagemode=ca
This is an excellent Remote KVM and IPMI card, which would normally be found in higher end servers, but is available for this little unit. The documentation is rather sparse, and if you need to access the device out of the box, the default username and password combination is admin and password. More information on how to reset this card if you have lost this password can be found here – http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c02681440&jumpid=reg_R1002_USEN