Xen Virtualization on CentOS

You can use many tools on Centos 5 to manage virtual servers:

CLI tools: xm, install-sh, virsh
GUI tools: virt-manager

Here are some useful links-

How to install a virtual server (after installing CentOS with the Virtualization packages):
http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU

That is a command line tutorial. But you could use virt-manager if you have X and Xen. It walks you though all the steps in a much easier way, but it is a good idea to know what is going on behind the scenes. Everything in this tutorial can be done by virt-manager without much hassle.

This is how you install a native virtualization DomU like Windows:

http://wiki.centos.org/HowTos/Xen/InstallingHVMDomU

It also has the way to check your processor extensions.

This one has some basics about keyboard mapping and also has how to deal with SELinux (without turning it off people!):

http://wiki.centos.org/TipsAndTricks/Xen

This article has P2V basics. It gives some insight into what the virt-p2v boot iso (linked in the intro post) does behind the scenes:

http://wiki.centos.org/HowTos/Xen/MoveNative2DomU

And if you had to move something yourself if you had to do it manually.