security precautionswith iptables?

[Littlefield, Tyler]

Hello list,
I've been told to block ping requests with iptables. I made the following rule:
iptables -A INPUT -p icmp --icmp-type echo-request -j DROP
The only problem with this, is it drops all pings incoming as well, which causes a slight problem.
Any way around this?
Also, is there anything else that can be done in order to make the system more secure? I was told to block fragmented packets. I know what they are, but don't know enough about tcp in order to be able to do much with them.
Help is appriciated.
Thanks,