Things like the capture effect apply to ethernet. If a host is fast enough
(and Linux and a fast NT box are) then any benchmark with ethernet is
pure trash anyway. Full duplex 100baseT you might get away with.
Having said that it may be that you are hitting other resource limits
first. It may be the Linux box is fast enough to drive the NT box out
of resources in bursts and SCO isnt (SCO is pretty slow as a TCP stack).
It may also be NT can shift requests fast enough Linux hits a resource
limit like total number of open sockets.
Alan