While investigating a ‘Low Disk Space’ warning on a workstation, I discovered that the user had been very dilligent about updating Java whenever prompted. This perticular workstation had no fewer than fifteen different versions installed, the oldest being JRE 1.4.2.

That said: Sun should really consider chaning the auto-updater to remove the existing installation before dumping the new one in. ~1.5GB of wasted disk space speaks to that.