Hi, I wasn't here when we purchased ours, but we use space observer - http://www.jam-software.com/spaceobserver/
It is a Windows based system that runs a DB and scans the file systems via the CIFS share. Our largest space it is monitoring is 2.5TB, it takes 30 to 45 seconds to load that and 17 others, with another 2.1TB file system in there, and three more over 1TB. Once it is loaded, the charts load in another 20 to 30 seconds, and you have line, bar, and pie charts. Customizable ranges, Top 100 Files, user based reports, etc.
If you want something with colors and pics for management types who want quick reference it is pretty good, while still letting you see detailed info.
- Scott