Server configuration for SBS 2011 standard

[qsnap]

Hello,

I am looking for some valuable views and advice which may help me build a proper system.

The server will be for 20 -30 peoples as a DC, DHCP, DNS (replacing sbs 2003) and exchange server for emails. Another thing important is that everything to get under 3000 £.

This dell system is under 3k on their website,

Intel® Xeon® E5-2430 2.20GHz , 2 x 8GB RDIMM1333 MHz, 2 x 600GB SAS 6Gbps, 3.5-in-15K drives in RAID 1 with SBS 2011 Standard (ofcourse for a ms exchange server 2010).

I'll be thankful for your suggestions.

[sukh]

Considered O365?