From your question, I'm assuming that you haven't already bought this server?
SBS can ONLY be deployed as a Domain Controller at the root of the AD forest. It cannot even be configured without a domain, so the easy answer to your question is the guy at Dell should have been sure that the answer is NO, you cannot install SBS into a workgroup.
SBS is a use-specific, preconfigured server which is intended to be the central backbone of a network with less than 75 users or devices. It cannot be used in any other manner, and if you tried, would power itself off after 14 days.
If you have a small network, SBS is a great value, and having a domain is always preferable to a workgroup since you can then centrally manage your systems and security.
Jeff
TechSoEasy