My gov't-issued NT4 workstation had a 520 MB hard drive in 1999, but everyone in a position to do so was going larger than that if they could. Can't remember what was "du jour" standard in sane workplaces, but I'd guess at a gig on account of it being twice what I had.
I remember having to admit this to a nice lady at Sams publishing when she asked why I didn't solve a problem with a "book on CD*" by copying it to my hard drive.
*Unix Unleashed, System Administrators Edition. Life and career saving book. Can't praise highly enough.