How to duplicate an installed Operating Environment

[dk_netsvil]

I wanted to start a thread about techniques that members have had experience with that can be used to duplicate an installed OS and set it up on other hardware. I am hoping to remain as OS-neutral as possible and open discussion for software that can be used on Linux, BSD, or Microsoft products. As an administrator I'm usually faced with a situation like this:

A machine running some necessary service begins to have hardware issues. There is a similar piece of hardware that is collecting dust, unused, in the corner. What can I do to copy necessary machine A to dusty machine B?

In the past I've used applications like (what is now known as) Norton Ghost, carbon copy, and server virtualization to create a backup of a server. However, these types of duplication tend to require some kind of downtime. Since I already accumulate several hours of unpaid overtime every week I would rather have, at my disposal, a tool that will allow me to create a live installable backup of an existing server. And, if it isn't too much trouble, a magic lamp which I can rub to get winning lottery numbers.

Can anyone suggest a software package that can accomplish this or point out a tutorial to the forum where additional reading can be found?

Below I have listed some links relating to Carbon Copy and Virtualizing an existing installation. They aren't exactly comprehensive, but if you've already had to perform this type of backup they suggest some alternatives:

Carbon Copy
Virtualizing Linux machines
Ntfsclone for M$

There is also this resource within this forum that is BSD specific using the dump command.

One method I've tested out is combining dd with netcat, but it is very slow and plays poorly with dynamic data. Because I could not locate my original source I will cite another equally good source:
dd if=/dev/my_harddrive | nc <remote_ip> <some_port> and over on the new residence: nc -l -p <some_port> | dd of=/dev/new_harddrive.

I tried this with a 2 gig install of FreeBSD and it took about 40 minutes to copy over, which seemed long. I wasn't able to determine if the bottleneck was the netcat command on the other box or the dd command that the data was getting redirected to. 2 gigs took awhile. 40+ would have been a nightmare.

But, it didn't require me to disrupt services although I did have to perform a dump and restore on the second machine to get the database working as well as change the hostname and IP.