PCSummarizer 2005 

Shows a summary of critical system information right on your screen! Information that is shown is customizable. Display can be on top of other windows, or not.
system summary cpu usage memory available hard drive space osd

PC Power Optimizer Lite 

PC Power Optimizer Lite has several categories and sub modules to optimize your Windows XP. You can customize menu appearance, Start menu and Taskbar, see system files, folder and change their settings. It provides privacy and security of high level.
memory optimization memory optimization registry cleaner registry cpu cpu information cpu resources junk files invalid registry entry history bandwidth optimizer internet optimizer

dtLibrary 

dtLibrary is a class library packaged as a single ActiveX DLL. This library offers multiple classes for retrieving and/or updating system information, including ini files, registry access, file/disk information, memory and power information, etc.
activex controls visual basic programming tips ini error hyperlink components ocx