Dual Athlon setup

I doubt it would recognize it after initial installation. But you could install Red Hat's SMP kernel package (rpm -Uvh kernel-2.4.x-smp.i386.rpm or whatever it ends up being called) and, if necessary, add the proper line to GRUB and then just boot that kernel.

That coupon on the 256MB chip is only good for one, so if you're buying two, realize you're only getting half the discount.