NT4 – SBS 2003: Migrate or build from scratch

We have a very small network, about 20 workstations (Win2K & XP). Domain is currently set up on an old Dell running NT4 SP6. Not a lot in the way of Group Policies, no DNS, basic office programs and some proprietary software.

We have bought a new HP Proliant server with Small Business Server 2003-R2, plus Exchange Server.
My question is, which would be better (read: less stressful) – migrate from NT4 or build a new domain from scratch and transfer files?

Links to online help sources would be appreciated.