There could also be a whole host of compliance issues for any company running SBS 2003 integrated software, including any Microsoft applications which will also no longer be supported. If you are considering NOT upgrading then make sure you have a couple of hundred thousand spare a year to pay for the support.
HP (the largest supplier of Microsoft servers) estimated there to be 11 million machines out there which will need replacing. That's 10's of thousands of machines needing to be replaced each day before the deadline.
According to a Windows survey 62 percent of customers don't have an upgrade plan (or a migration to the cloud plan), or are not aware of this deadline.
Our advise is to start getting ready to migrate or upgrade. Our preference these days is migration to services like MS Office 365 for which we provide high level consultancy, and implementation. To find out more contact us now.