If I was on a dhcp network (such as resnet) I would just set up my eth0 (first ethernet card) to get an address via DHCP.
You can do this one of a few different ways, but editing the file is the coolest way - you are way leet doing it this way!
1 - Go into /etc/sysconfig - this is where your bootup config scripts are.
2 - Go into the network-scripts directory and edit the ifcfg-eth0 file.
3 - Add the following three lines for DHCP:
DEVICE=eth0 ONBOOT=yes BOOTPROTO=dhcp
4 - Save file - restart computer, or networking by doing a `/etc/init.d/network restart`
By now you should have networking, type `ifconfig eth0` to see if the interface has an address.
If not, then you should troubleshoot this more, or try some of the other utilities some more till you get it.
If so, then move on to looking at your firewall configuration.