Power supply, Standard ATX. Any decent PSU will be fine. I like modular so you can remove the useless PCIe and sata cables but that costs a bit more.

Case, also standard ATX. Finding one with drive bays and you like the looks of will be the biggest challenge.

RAM, 256or 512MB is the sweet spot for Win98, SD ram is backwards compatible so PC66, 100, 133 doesn't matter. Whatever you can get a good deal on.

Graphics, You can upgrade the CPU to a P2 333 so think a GF2MX is good in this 266-333Mhz range.

You can probably use Celeron 533 (Mendocino core - black one) with Slocket.
The rest - I agree with chinny22

Thanks for your input - I really appreciate it. I'll start looking around, and agreed - the case is probably the most difficult to find. (Especially if you wan't one in white/beige like I do.) I'll post my setup when I'm done.

Thank you kindly.😀

retroguy83 wrote on 2021-02-10, 11:04:

the case is probably the most difficult to find. (Especially if you wan't one in white/beige like I do.)

Only if you want then new. People don't value those old beige/white/off-white boxes. If you look hard enough you might get one for free. To be fair, if you don't want to get fancy you can get most of what you need for free. Except the PSU. New PSUs cost money.

retroguy83 wrote on 2021-02-10, 11:04:

Thanks for your input - I really appreciate it. I'll start looking around, and agreed - the case is probably the most difficult to find. (Especially if you wan't one in white/beige like I do.) I'll post my setup when I'm done.

Thank you kindly.😀

Depending on where you are located it should be sufficient to go to the local classified ads platform and search for a generic term like "old PC", because this is what most people see 😉

Had a Sun Solaris build back in 1990’s with a dual slot-1 intel 440lx motherboard.
I used SCSI drives and ATI play-98 video card.

But a period correct video card might be the Riva tnt or Riva tnt2.

You'll need low density memory modules for the 440BX or LX boards. So maximum of 256MB capacity per module, and if it's 256MB, then the memory module should have 8 memory chips on each side.

Graphics - an AGP card that's backwards compatible with the 3.3v AGP 1.0 standard. The card should either have two notches in its AGP connector, or one notch that matches the position of the key spacer on the board's AGP slot.