I agree that IPTABLES is much better than IPCHAINS...the main reason is because it is a stateful firewall. But jc is exactly right...there is far less information and documentation available for IPTABLES. If you want a web management interface for it, you might want to check out the third-party modules for webmin http://www.webmin.com

I know they were working on the module, but the last time I tried it, it was still in alpha, so it was not very good yet, but give it a try.