I have a Windows XP computer that belongs to a Workgroup. It prints to a local Canon USB printer. I use it to RDP into a Windows Server 2003 machine. The Windows Server 2003 machine belongs to a domain. During the RDP, I select the option of including 'Printers' in the 'Local Resources'. However, I am unable to print from the Remote server to the local Canon printer.
Has printer redirection been enabled on the server? If the server doesn't permit it, there is nothing you can do on the client.
With Windows 2003, there is a lot of issues with printer drivers and printing over RDP. It could be that a compatible driver mapping could not be found. If Citrix was installed, or if you had Windows 2008, then a generic driver would be used.