Firewall, roadrunner, mac question

[IanB]

Here's my question:
I am running a linux box (TurboLinux Server 6 on a P-90) as a firewall to connect to roadrunner.  
It connects great for my linux and win98 machines.  
Recently, my wife just got an apple i-book that she (and me) wants to connect to the net through 
the firewall.  I have very little experience with macs, but I figured it couldn't be all that hard. 
 I set up the TCP/IP with the same settings as I would on my other computers.
Problem is, it connects but it is v-e-r-y slow.  Too slow for my patience to handle.  Does anyone 
have experience with a similar situation?  Do I need to install a proxy on my firewall?  I have run 
searches for information on the web, but I cannot come up with anything useful.  Any good links I 
should look into?  Any help would be much appreciated.