I think that if you look HERE
you might find what you need.
edit sysctl.conf, put this in:
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
Quick note about the above instruction and the script in the post I linked to....
The file is /etc/sysctl.conf
I've long suspected that your issue was simply that your RedHat box wasn't routing and this line apears to be what tells the box to route IPv4 traffic. This should allow request hitting your RedHat's LAN interface to be accepted and pushed out through your PPP interface.
As to your comment that your'e not using PPP0.... I think that if you go to a command line and type: ifconfig you'll find that you are infact using a PPP interface, the friendly little GUI in KDE has simply hidden it from you.
I realize that this post may fall on deaf ears as I've read your post about giving up; however, I've also read many of your other posts about giving up so I'll take this one with a grain of salt. If you don't get the fix perhaps this will be helpful to another user.
I am truely saddened that you have had such poor experiences with Linux as it is probably one of the most flexible operating systems I've had the pleasure of working with.
Again, I hope that your post about scrapping Linux for WinXP as your gateway OS of choice was simply done in spite and not your true choice. If you care about what is on your computer and do not want the entire world to be able to see it, I STRONGLY suggest going with anything other than a Windows Workstation OS. At least go with a true Server OS like Win2003 WebServer edition. I'll even post a PDF about securing this operating system so it can sucessfully be used in a live internet enviroment.