<< The BIOS should be able to handle up to 8GB natively? You should be able to add a PCI controller board to allow up to 128GB drives. In any case, I'd use an add-on controller. >>
That's assuming it even has PCI slots, which is probably does not. Most 486's had VLB or pure ISA only slots. Expanding the RAM would be a bitch too, since it's likely to use those old 30 pin simms.