I had a virus/trojan, used avg to remove it and I'm not sure if it's gone, but I'm working on that in the spyware forum, now I have installed all the updates for XP and my processsor is like working double time, all I'm doing is watching a tv show on the computer, and the processor is like 70% normally it's never above 15% and I thought that was a lot.

My computer is now running so slow, and I only installed the critical updates, and the security updates I thought but I'm not sure.

I had this problem before which is why I didn't update windows, which ultimately led to the virus exploiting the holes of XP.

so my question is what updates are truly needed, and do they have anything to with my computer being slow? or is it something else?

and sometimes when I click the security center icon in my taskbar it disappears and sometimes it will open but I'll get an error that says explorer needs to close.

What is listed under winver?

start/Run winver

Also do you have a retail version XP CD? Or is your XP an OEM (pre-installed) version?

You might be best off running a Repair or Recovery Install of XP.

I have the cd and its Windows XP 5.1 SP2 with all the current updates. I thought it may have been that I set the page file to C: so I changed it back to original.

How long has this version been running?

At some point if you encounter continuous issues it is best to run a Repair Install for a fresh slate.

A Repair Install will not affect your programs or settings.

Details here:

http://michaelstevenstech.com/XPrepairinstall.htm

And here:

How to perform an in-place upgrade (reinstallation) of Windows XP

I'm not sure about 3 months I think.

if I do a repair, then will I have to download all the other updates again?

If your disk is SP2 then you will have SP2.

Any updates after that you would have to reinstall if you want them.

it's only an sp1 or maybe just a plain install it's kinda of an old disk like when XP first came out.

I found a post on another forum how to create a boot up cd, but I wanted to ask you what updates I need and what ones I don't because as of now I have them all installed as I mentioned before.