I upgraded my computer to FC3 and started it up with the newest SMP kernel, but it still refuses to talk to the network card. I've also found that when I boot the computer with the SMP kernel, it doesn't see my USB ports, which mean my mouse and my Palm cradle are left out in the cold. So I'm just going to stick with the regular 2.6.9-1.667 kernel for now, and not worry about the SMP kernel; because of the USB issue, I'm guessing that there might be something a bit more sinister going on than a mere broken TCP/IP stack (or whatever is causing the network problems), something related to my motherboard. Thanks to everyone who offered suggestions and ideas. Incidentally, I'm using the older .667 kernel instead of the newest one because apparently there's a bug in the newest kernel which causes the gnome-pilot applet to crash, causing problems when I try to sync my Sony Clie NX80 up with the computer. Using the older kernel and making a couple of minor udev adjustments lets my Clie talk to my computer just fine.
