I made a complimentary package for PimpShell (yes, this is for XP only) containing very useful selection of freeware that less than 1Mb each.
M$/Sysinternals Regmon and Filemon, a good educational tool (newer replacement is much slower)
M$ Tweak UI
Powerquest Partition Table Tool (also available here)
PowerOff, automate power off (homepage)
ResHack, the old still popular executable's resource tool (homepage)
ProcessHacker (OSS), why? Process Explorer is overkill
Regshot (OSS), monitor what happened to your Windows before and after an event.
Greenshot (OSS), the best screenshot tool whether commercial or not! (need dotNET)
Name Generator, generate random username (homepage)
Notepad2 (OSS), this is what notepad should be
Mike Lin's StartUp CPL, there are something more out there but this one much smaller (homepage)
GrepWin (OSS), Search files and content with RegEx power
Showin, the old tool to show window handler of application
Angry IP Scanner 1.9 (OSS) (newer version is Java based)
Warning: Partition Table Tools is not for casual user, don't mess around unless you know MBR concept
No need admin right to install, but you'll need it when running most of them
To uninstall go to Add/Remove Programs
MiniToolsXP_Silent.exe (2Mb) Enjoy!