If you are migrating from one guest host to another using VMWARE and have problems with reusing the IP address from the old host, VMWARE may be binding the IP address to a MAC address. Even with the old server off, I was unable to get the new server to bind with the original IP address.
The fix is to create/set a network adapter on the new server with the MAC address of the old server. After setting the MAC address on the new box to the original NIC MAC address, I was able to get full connectivity with the old IP address.
This will only work if both hosts are on the same VLAN, the original host was using a flexible network adapter, and on the same VMWARE server cluster.