Virtual machine manager is the graphical tool used to manage virtual machine.
it was only available in 64bit installation.
you can run the tools from Application > system tools > Virtual machine manager
Virsh command allow you to manage your virtual machine
Here are the some command to use with virsh
# virsh list
# virsh destroy <server name>
# virsh list --all
# virsh start <server name>
# virst shutdown <server name>