For a project at work - yes, I was a generous soul - I requested a PC which had 2x 540 MB drives (from poor memory, and don't ask what else there was in terms of RAM, but it cost over a grand, and that was deducted from my salary over the course of the year - while I was using it at work and yet buying it for my own use!)
Anyway, that was late 98 or into 99 and probably using WIn 98. (As an aside, I remember the support guy at Microsoft who sounded like his jaw had dropped when I told him I was processing 1 million records in MS Access.... and boy was it slow when I had to 'compress' to remove the deleted records (going from drive to drive, so they were not being thrashed too much compared with a larger capacity drive and both source and destination being on the same drive.)