I should have thought of this eariler.
Reduce the bus speed from 133MHz to 100MHz. So the RAM essentially becomes DDR200 and my AthlonXP 2000+ goes to down 100 x 13 = 1.3GHz.
And the installation goes through smoothly now, since I put a fake physical limit to my hardware. Still, it would be wise of Blizzard to produce an alternative installation program that can throttle the CPU so that the burden isn't so severe.
How about gameplay? I dunno. I just patched this game, and am going to reboot back to normal specs and see how it goes.
Update: I'm so obssessed with World of Warcraft..... help.