My setup is somewhat different from Refalm's, but it's still supported pretty well in Linux.
Pentium 4 2.8Ghz Prescott (I wish for Northwood now
)
Video: GeForce FX 5700
Sound Realtek AC97 onboard. Detected perfectly in Mandrake, Fedora, and even Slackware.
Network: Marvell Yukon Gigabit Ethernet, onboard. With modern distros, a simple "modprobe sn98klin" gets the card working nicely. Also I have a Linksys WUSB11v3, which has spotty support due to differing chipsets and NDAs on the datasheets for them. I haven't gotten it going yet...I think I might have the Amtel version now, but I've been trying the Prism2 drivers.
Motherboard: simple Intel i865 chipset. No problems.
That's about it for me. I don't have any special components - no local printer (networked), no digital camera, no webcam, none of that. Not to say those things never work - some of them do, I just haven't had to try.