OK, There is one way that works. I'd suggest using it. Most server OSes now have some way to make a virtual hoist. Solaris has zones, Linux has xen and there is VMware. The idea is that you build the new updated web site on a new virtual host. and then you test it. Once you like the tst results you swap IP addresses. You don't really want to go live with changes that are untested. The IP address is "atomic" in that the entire site goes live at once.
BTW I've always liked the way Solaris does this in that you can have many "zones" each with their own IP address and file system but there is only one instance of the operating system running on the hardware. I always thought it a waste to have multiple copies of the same software in RAM, Sun solved that problem well. -- ===== Chris Albertson Redondo Beach, California