Proxy and Firewall Recommendations?

["Scarletdown" <gsutton9503@charter.net>]

I'm about to embark on my next project, getting a Debian system set up as 
a proxy and firewall.  This is going to be the system that my roommate 
will be connecting to as his gateway to the Internet.

He is running Windows-98SE, and the system that he is currently 
connecting through (the same one that I will be putting Linux on) is also 
running 98SE with ICS.

So, what I need to know is, what would be a suitable set of packages to 
download and install for routing and firewall services for him?  Since I 
want to have this system operational pretty fast, I need something that 
is fairly simple to configure.  It should also be able to block outgoing 
stuff from his system that he doesn't want phoning home (that would 
include Windows Media Player, RealPlayer, and any spyware, for example.)  
I also need to make sure that the MMORPG that he has become addicted to 
can be played through the firewall.  The game is Horizons, and it is 
played through Internet Excreter exclusively, unfortunately due to its 
use of ActiveX.

Any suggestions for this project?

Thanks.