1)   power Informer XP 2 v3.0
Powerful tool for monitoring system activity with rich Graphic User Interface. It is very easy to use and it is very useful tool for professional, because that can quickly acces to all system information, but also it is very useful for beginers.
system info, hardware info, software info, WMI, active applications, enivironment variables, disk space, free disk space, active connections, TCP/IP,

 2)   More Space Sanitizer 5.0
Safely reclaim and sanitize disk space by deleting duplicates and file hogs. Identifies duplicate files, file hogs, folder hogs, temporary files and more.
morespace, diskspace, free disk space, disk utility, sanitize,

 3)   VisDir Free Disk Space Finder 1.4
This free user-friendly utility helps you visualize which programs on your hard drive are using too much disk space. It creates a navigable pie-chart visualization of the space utilization on your computer. Freeware with no expiration.
free disk space, free space finder, disk explorer, disk utilities,

 4)   More Space 4.1
Safely reclaim disk space by deleting duplicates and file hogs. Identifies duplicate files, file hogs, folder hogs, temporary files and more.
morespace, diskspace, free disk space, disk utility, more free space,

 5)   Duplicate File Killer 1.8.5
It can scan and delete all duplicate files and zero-sized files on the hard driver. It can scan and distinguish from filename, extensions and date. It creates lists of duplicate and zero-sized files.
delete duplicate files, remove duplicate files, delete zero-sized files, remove zero-sized files, free disk space,