Good XP/Vista Optimizers?

I’ve been working on computers for a while now, just small stuff, anti virus, tweaks, general maintenance for friends and people i meet. Through this, i’ve started a small list of programs and reg tweaks i like, but i know there is a lot more. I’m just wondering if anyone has any suggestions to what they use or like. I put a quick list of things i use together, they include the following:

AVG anti virus
Spybot S&D
Regscrub
Defraggler
Autostart
TuneXP
TweakUI
Revo Uninstaller
Sys Properties>Performance>Visual Effects
Comodo Firewall
HiJackThis free
The built in "disk clean" option under My Computer
Random Group of Registry tweaks I kinda put together

Any advice is appreciated. They can be programs or reg tweaks. I prefer freeware, but i am willing to pay if they are really good.

Thanks

I have the following free programs in my PC: Malwarebytes Anti-Malware, Comodo Internet Security, Wise Disk Cleaner 4, Wise Registry Cleaner 4, Advance System Care Free, AVG Anti-virus and REVO Uninstaller. What software is not important and should be removed in my PC? Thank you very much!