Could you please give a more detailed info about the hardware? Like the exactly amount of RAM, the exactly processor model, video card, etc.
If you really have only 555k of RAM that might make things difficult.
About the hard disk, I don't think a 486 BIOS can handle a 80Gb ones, maybe 20-30Gb disks, I do have one that can't handle anything bigger than 30Gb and it is an advanced model of 486.
Just for a start here some links of interest: