http://community.citrix.com/display/xs/Configuring+CentOS+5.5+Guests+on+XenServer+5.5+and+5.6
http://www.cyberciti.biz/faq/linux-find-out-the-name-of-dvd-cd-rom-writer-blu-ray-device/
If you have two NICs you have to ensure that the NIC on the physical server that is connected maps to the Network property that the virtual machine will be using….
For example,: Network 0, Network 1 are the default networks on Xen. If you only have an Ethernet cable in one of the NICs then one of the two Networks will be available. This is important to verify when you ‘re setting up a new VM so that all your configuration settings for eth0 or eth1 are mapped to the proper Network # in Xen Center.