What happen with a Windows 2003 SBS license if I go virtual… ?

Hi
I have a windows server 2003 small business server and want to migrate it to a virtual machine in Virtual Server 2005 R2 or alternatively to a new hardware due to a hard disk failing and old hardware.

How can I carry the win2003 license to the new machine virtual or real? is it possible?

Alternative suggestions also appreciated.

Thanks in advance
Regards,
Pablo