I use ccleaner, hijack this, Vcom system suite registry cleaner and registry defrag.

I use ccleaner , but found this one still finds more even after running ccleaner , and best of all it's another freebie

ToniArts EasyCleaner 2 ( it also makes backups )

Finds invalid registry entries ----> deleting them speeds up your computer!
Finds duplicate files ----> deleting them will free disk space!
Finds all unnecessary files like backups, temps etc. ----> deleting them will free disk space!
Finds all invalid shortcuts ----> deleting them will free disk space and increase usability!
Manage programs starting at Windows startup! ----> who knows, you might even catch a virus before it gets serious!
Manage Windows add/remove software listing!
Easily remove Internet Explorer's temporary Internet files, history and cookies!
Very user friendly!
Shows some interesting info about your disk space usage.
Very customizable.
Multi-language support!
Uses only little amount of recources while running!
Huge help file which gives you every little detail about EasyCleaner!
And much more...

http://personal.inet.fi/business/toniarts/ecleane.htm

CCleaner, RegScrubXP, Eusing Free Registry Cleaner and Free Registry Defrag. They all find different things for me. MRU-Blaster for mru's.
 
Installwatch, inctrl, or Revo Uninstaller to monitor installations. I've tried them, but i'm not sure which of these is better. These programs take pre and post install snapshots of the registry and i believe system folders and give you a list of all additions, deletions and changes when the installation is complete. One of these programs, I forget which, gives you a choice of .txt, .htm(l) and another format for your output list of changes.

Sandboxie to test programs without installing anything on your system. It installs everything into a, "Sandbox." When you're done, delete the sandbox and everything is gone. Nothing gets loaded into the registry or program/system folders. You can install and run a program through it, run any program on your system through it, or even run your web browser and surf the net with it. If you like the installation you can, "Recover" it, (load everything or chosen files onto your system from the sandbox without having to close sandboxie and re-install your program.)

The cool thing about Sanboxie is that you can load one of the above mentioned monitoring programs into it and track another install from within the sandbox and then delete the program and the install monitor when finished. Another positive is that you can use programs through the smaller installer files while sandboxed and save hard drive space by never having to actually install certain programs.

These are all free programs.

i have auslogics boostspeed,ccleaner and registy mechanic

CCLEANER (formerly Called CRap cleaner). A wonderful program.

I use CC/Cleaner but, I’ll give that Easy Cleaner a chance. 

I dont haue a registry to bloat out the OS, if I see something I dont want in the library, I toss it in the trash, and its gone, no worries about parts and pieces laying wherever they were just thrown. Litterally !