Here's a couple pictures of the original machine. (apologies for the bad angles)
I have identified the Apex Supercase 100-G2-P4 as being a close match, with the only identifiable difference being the lower half of the front panel being laid out differently.
An example of an exact case match to the machine is this listing for an AMD Duron machine on eBay.
Regarding the inconsistencies relating to where the front USB ports are on these cases-- they're 5.25" inserts. It's way more noticable on the image of the Duron listing than my original one-- zooming in it becomes more obvious.
[ edit - 4h after post ] Another match found. Still no known searchable name? I would buy this if I were actually in Australia
another observation about the differences: the eBay listing has an NTC sticker and mine had a Sound Blaster sticker. was this specific sticker size common back then??
I can recall using this case at the time it was new, or at least one with a similar front panel and no rear exhaust fan. It was informally called the "purple button" case for that distinct detail.
Cost like $35 back in the day with a 250-watt Deer brand fire hazard class PSU.
Many cases had a 1x1 inch opening for a manufacturer logo sticker. This trend goes back to the original IBM 5150 and people wanting to make close match looking cases and seems to have died off after the Core 2/Athlon 64 era, likely as small white-box PC shops disappeared.