How to run a web application from remote IIS server?

I have a old server(win2003, IIS6.0) which run a couple of web applications,
it is our web server now. recently I bought a new dell server which is
running win2003 with IIS6.0. I want to migrate all web applications to the
new one, but it has not been setup as our web server now.

I want to keep the web applications in the old server for a mement, at the
same time i would like to run a web application which resides on the dell
server from the old server. I'm think perhaps i have to set up a new virtual
server or a virtual direcotry in the old server and point it to the new dell
server.

But I don't know how to configure it after I created a new virtual server or
a virtual direcotry. should I map network drive or UNC and how these two
servers can trust each other, I mean how the security in both of IIS and the
web application folder permission setting should be configured?

thanks in advance
Bo