I'm wondering if a ubuntu pc can act as a server to provide the ability to network boot ubuntu's live cd to other system(s) in the network.
To make my question more clear:
From Wikipedia's article on Network Booting:
The initial software to be loaded is loaded from a
server
on the network; for TCP/IP networks this is usually done using the Trivial File Transfer Protocol. The server from which to load the initial software is usually found by broadcasting or multicasting a Bootstrap Protocol or Dynamic Host Configuration Protocol request. Typically, this initial software is not a full image of the operating system to be loaded, but just part of it - enough for the operating system to start and then take control of the booting process, and continue booting over the network.
I want to make one ubuntu pc as the "server" and enable the other pc's to be able to boot from a ubuntu image I host on the server
PXE (Preboot Execution Environment) is what you're probably looking for. With it you can boot many computers up to either an install process (so you could install Ubuntu on a dozen machines at once) or a desktop setting. There are a billion and five separate guides rotting in the Wiki but here are two of the best I've seen:
Straight PXE booting like this creates a "fat client". All the computing happens on the client end and (by default). This is good if all the clients have enough computational power but less good if you'd rather have a powerful server and lots of underpowered "thin clients". There's also no effort (by default) to sync users or their files.
If you want to continue the idea to booting full desktops with sync files, you should have a look at LTSP. It supports both thin and fat clients and is good for proper deployments with multiple users.
I've thought about this before but my main problem with PXE is you need to set up a separate network with its own DHCP server. It can all be done from within an Ubuntu desktop but it can get pretty complicated when it comes down to joining the two networks. If you want the Live CD clients to have an Internet gateway, for example, it gets pretty hairy. Extremely possible but it can give you a headache.
It's documented on the ubuntu wiki here.
Multi-boot is detailed here.
A combination of the two should get you exactly where you want to be...
The first one gets you booting across the network and pretending there's no disk. The second one shows you the BootLocal option.