Process Tamer - Freeware Microsoft Windows utility that monitors the CPU use of applications, alerts when they use too much, and reduces their priority to keep your PC fast.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
Big Meter Pro - Big Meter Pro is a utility that monitors the disk and memory of your CPU.
WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.
SSuite System Monitor - SSuite System Monitor is a completely portable and stand-alone application that monitors the RAM of your system, page file load, CPU usage, and the system power in real-time.
SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.