A lot of good suggestions here; my personal view is pretty in-line with what's been said already; as far as the boards I'll say that I did *not* like the DFI LanParty KT400A; the NF-II B Ultra is generally a much better board. From Abit you have both the NF7-S and the AN7 as good choices.
Another idea would be to go with a dual-462 board and either a pair of XP-Ms (for some reason they're unlocked for SMP) or AthlonMP 2800s and the same from above - you won't have as much OC'ing as an NF2 with an XP-M, but you'll have two CPUs!
Graphics wise, the FX 5950 or 9800XT would be "era appropriate" for TOTL; the 5900XT and 9800SE were popular choices for overclocking (and in the case of the 9800, unlocking) on a budget though. The 9600XT was/is also a good choice. If you're digging around used cards, the 6600GT AGP would also be a good choice as well. Or, if you can find one, an AIW X800 AGP. If you're going beyond the 6800/X800 series, there won't be as many options - there's only a few AGP cards from the GF7/X1800 era (they all use bridge adapters).
PSU wise PC Power & Cooling was/is a good choice, the Fortron 530W was a popular choice, as well as the TTGI/Superflower 420W; anything that can supply sufficient power should work though - honestly unless you already have said PSU, I'd just get something modern in the 400-600W range instead of dealing with a used unit.
Cooler wise: Thermalright made a number of popular coolers, including the SLK-800 and 900 and the SI-97; Thermaltake had a few popular hits as well, most had "Orb" in the product name, and finally Zalman with their huge copper or copper/alu hybrid models. There should also be waterblocks available for 462. Keep weight in mind though - the heatsink clips to the socket like S370.
Soundcard wise: the SoundStorm built-in on the NF2 Ultra is good, and will do DDL, but if you want discrete the Audigy 2 ZS and ZS Platinum were "it" back then. M-Audio also had the Revolution which was mildly popular, along with the Chaintech 710 (which is similar but was much cheaper).
AFAIK you could run XP or 98SE at will as long as you don't have a GF7 or X1800; the GF-FX and GF6 should support 98, and I'd assume the 9800s do as well. I do not know about the X800 and 98 though.
EDIT
Forgot to add: if you need DVI output, some of the lower-model GeForce FX and Radeon 9 cards (like the FX 5200 and Radeon 9500) tend not to be the best choices if it has to be high-resolution (like 1600x1200), as they tend not to be able to provide the full bandwidth 165MHz connection. The later cards from that era, like the 5700/5900 and 9600/9800 boards tend to be good-to-go for single link. If you want DL DVI from a card from that era, the Quadro FX 2000 (GeForce FX 5800) and FX 3000 (FX 5900) offer one DL DVI output, and have very high quality DVI on both of their outputs (they use external transmitters for everything). I'm not sure about the FireGL X1/X2 boards and DL DVI, but also note that some of those boards are AGP Pro (and will not work in a normal AGP slot).
Price-wise an FX 2000 or FX 3000 should be comparable (perhaps cheaper - I've seen some pretty high prices for 5950s and 5800s over the years); for example a quick look on ebay shows a lot of FX 2000s for right around $20, and FX 3000s for around $30-$40 while FX 5900s seem to run from $40 to $80, and 5800s seem unavailable.
Here's an article from ExtremeTech about the DVI thing: http://www.extremetech.com/electronics/55254- … liance-shootout
Random thought based on the above: I'd probably go for a Quadro FX 2000 if you're on a budget - $20 and it gives you better DVI connectivity than any GeForce FX board, and performance on-par with the upper-tier of the GeForce FX lineup. AND it doesn't have the super-blower cooler. 😀
