Network Slow since migrating to SBS Server 2003 R2

We had a peer-to-peer network with 10 workstations, but we migrated to a DELL PowerEdge Server with SBS 2003 R2 32-bit installed. We connected all 10 Windows XP-Pro workstations to the server and now we are experiencing a VERY slow network. Any suggestions? It’s taking forever to launch all software from the server.

Help!!