When I used a 4.3Gb HD, back in the day, I had:
Sys: 330Mb (clearly an overkill, 100Mb is more than enough)
Work: 700Mb
Games: 1.9Gb
Other: approximately 1Gb (anims, music, photos, miscellaneous)
Downloads: 400Mb (good for those apps and games you swear to put in the proper location some day)
OS3.9 don't have partition size restrictions, like old 3.1 and less. Just be sure the Sys: partition is under the 4Gb barrier.
