minimal iptables ruleset for laptop

["Volkm@r" <plsdontreply@arcor.de>]

Sorry for this newbie question - I'm just learning about iptables.

What I have is a laptop that I want to protect against external
intrusion. Relevant interfaces are

- eth0, which is LAN and sometimes DHCP sometimes pppoe
- eth1, which is WLAN and sometimes behind my private AP
        and sometimes behind company's or public APs

Of course, this laptop would never have to act as a router.
I want to prevent any external intrusion but be able to connect myself
to any external service. AND I want to be able to run some services
(X11, CUPS, Tomcat,...) just for myself.

From somewhere on the internet I got the following snippet which I think
may be suitable for ppp0 as the only interface. But I couldn't find out
how to change it for my needs.

-------------------------------------------------------------------------
# Generated by iptables-save v1.2.11 on Mon May 23 15:54:20 2005
*filter
:INPUT ACCEPT [10502:1065067]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1529512:141800679]
:block - [0:0]
-A INPUT -j block
-A FORWARD -j block
-A block -m state --state RELATED,ESTABLISHED -j ACCEPT
-A block -i ! ppp0 -m state --state NEW -j ACCEPT
-A block -j DROP
COMMIT
# Completed on Mon May 23 15:54:20 2005
-------------------------------------------------------------------------

Any help will be much appreciated.
-- 
Volkm@r