SBS 2003 Sp1 removing servers into own environment

I need to remove servers from a network into its own network with Firewall
and Router yet share resources with the original Network running SBS 2003 Sp1
in AD. What is the best practice? Commity is considering Workgroup and
traversing the two Firewall DMZ, is this good practice? Does SBS 2003 R2
allow for trust relationship? Can I have multiple Domains with SBS one in AD
and the other without?

Thank you,

Al
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Reconfiguring a network I enhirited your assistance is appreciated....