>As far as XML being inherently faster over the wire, I doubt it. XML, especially for sizable datasets, suffers from the considerable bloat inherent in it's syntax (opening and closing tag pairs).

It depends on what you're doing. XML is actually not as bloated as it seems even with the tag overhead. Reason is that it's highly compressible. In Internet Scenarios I've found that raw XML transfers can be often as fast or faster than comparably compressed files, because the protocol encryption (in a modem or net adapter) can take the bloat out.

DCOM, however, once connected can be very efficient. But it also requires a persistent connection to the server (or else you get the overhead of a reconnect each time which is dreadful).

In general I think DCOM is not a good choice for anything but distributed components that must access content on remote machines on a fast network. For remote connectivity of application clients - there's too much baggage in terms of security, network administration and installation involved to make it really a good choice.

DCOM is supposed to be able to run over HTTP in Win2000, however, I haven't looked into how and if that actually works.