If you're going to play Alice, the Ti4200 is the way to go; The Voodoo3 (any version) has nowhere near enough power for Alice unless you wish to relive the days of 15-20fps gaming. Plus, Alice needs to be played in 32-bit color, but textures can be dropped to 16-bit without too much loss of fidelity; but why bother? The Ti4200 is more than ample, plus AA and AF to play above 60-85fps at 1024x768.
You could put both cards in the machine and swap cables or VGA switch on reboot, as you've alluded, for games like Diablo II. Quake GL and Half-Life run and look fine on either card. If you play any DOS games (which aren't too speed sensitive, but there are workarounds) will play fine on either card.
You should be able to build any Pentium 4 machine cheaply from around the turn of the century. Athlon mostly the same. As soon as you get to the faster Northwood Pentium 4s' it's a wash between AMD and Intel. Plus, you're no longer using the machines as a daily driver, encoding machines, or creating multiple spreadsheets, so there's no benefit to be had from the days when one was better than the other in certain areas. As you'd expect, getting to the extreme performance ends of performance for either platform raises cost; sometimes substantially.
Creative Sound blaster Live!, Audigy, Audigy 2, Audigy 2ZS are all fine. If you can find a Vortex 2 which doesn't cost an arm and a leg, it's a stable around these parts. Moreso for late 90's, and perhaps 2000/01. If you're playing later games, than the Creative cards become more important. Of course, you could put both in the same machine, if desired. All cards can be used in DOS with varying degrees of compatibility based on motherboard, OS, and games. But if you put that 200 MMX to work, you should be able to bypass all DOS tomfoolery (speed sensitive games, notwithstanding).
The one size fits all "Holy Grail" machine is an illusion, heh. You'll have more enjoyment putting two machines together, anyhow, and you can have two masters of one instead of one master of none.
