In a dual-NIC configuration, some Windows NIC drivers do not behave properly when sharing the Windows active NIC with the primary NIC for Tru64.  Symptoms may include poor throughput, packet loss/re-transmission, or even Tru64 UNIX 0x670 Machine Checks associated with incoming broadcast packets.  The solution is to use the recommended configuration of dedicated NICs for the virtual Alpha.  There is a wide range of NICs and associated drivers available for Windows and many will not exhibit this shortcoming.