I have Fedora Core 3, kernel 2.6.9-1.667 on a Dell Inspiron 8600. Recently after some ill-fated network adjustments (like trying to make it see my wireless card -- BAD IDEA) it started booting up really slow. The full boot-up process takes a good SIX MINUTES! The system config network gui also fails to start.

In particular here is the stuff that takes longest to load. Left column is screen message, rightmost column time in seconds or minutes:

starting udev takes about 5 seconds
Initializing hardware 30
storage 5
network 2.5 MINUTES
audio 30 seconds
Checking for new hardware 30
Applying iptables firewall rules 20
Starting hsf 45
Starting pcmcia 10
Starting cups 10
Starting sshd 10

The rest seems to go fast enough. Also, upon logout, stopping iptables needs about 20 seconds.

Any ideas will be appreciated. In fact, I would be eternally greatful to whomever can help me bring the booting time back to acceptable levels!

Your wireless is probably set to start on boot and, since it's not working, waiting for a timeout. Go back to the network configuration dialog, and disable the "autostart on boot" checkbox.