how do i disk clean up and is it good to my computer. Will my game files and pictures and games be delete it? is it normal to do that?

Basically I want to get rid of everything I don’t use or need, but so many things are interconnected that I don’t know what I can and can’t get rid of. Plus I want to completely rid my computer of adware, spyware, etc. Some of that stuff I just can’t get rid of. What should I do? Or what is a reasonable price to pay someone else to do it?

I have an external hard drive, and I guess it’s full so i can’t download anything else on it.

How do I clean it up?

Will simply deleting a file actually work?

What about defragging it?

clean install windows xp?

i bought a xp pro sp3 installation disc but after the installation process i still have my old junk. (i have win xp pro) how can i clean install it???????????!!!

DO YOU RECOMMEND NORTON SYSTEM WORKS FOR AMONG OTHER THINGS CORRECTING REGISTRY ERRORS. OR CAN THAT MESS UP YOUR COMPUTER?