Making an older computer new Options

[Maccabee]

I am currently on a desktop running xp(my favorite os) and it used to be somebody elses and I had a few questions.

1. How can I remove programs properly without leaving regisrty files and junk which eventually slow it down.

2. How can I change the full computer name.

It was music box but i changed it to CohenComputer. But music box keeps coming up all over the place. More about that will be explained in a minute.

3. When I go to documents it doesnt show the My videos My music and My pictures buttons.
When open the folder ARCHIVE_THIS_PC I see them with their little icons. I tried to just copy and paste them to my documents which worked but then whne I open the start menu the shortcuts to the right changed from My Music and My Pictures to Cohen's Music and Cohen's Pictures and I cant click them! ANd when I right click them and click properties it says the location is blahblah\Music Box\documents\Archive this pc\my pictures or whatever. Weird I know!

So if I oculd have resolutions for those that would be great or if I could find a way to pretty much reset my computer or format it but keep the os. Cause I dont have an xp disc.

[Maccabee]

I havent reformatted it. It has alot of expensive programs on it so I dont want to reformat it. And I havent backed it up.

oic. sorry, i just assumed that was the main reason you wanted to get rid of things on the computer.

Well I want to make it run like its new but not get rid of the files and some programs.
Is there anyway to put a program on a flash drive and put it on another computer and it work?

- reformatt (some computers give you this option without the need for the startup/OS disks i.e. - dell, HP)
- uninstall useless crap
- use a registry cleaner program
- defrag
- chkdsk

I put that into cmd and it started and said it was in read only mode. When it finished it said. Errors found. Can not continue in read only mode. How can i turn off read only mode or whatever?

Reason for edit: Please don't triple post. If you have something to add to your post, click "Edit". If you continue to triple post you will be warned. Thanks.