Can I safely delete old Windows Security Updates

I doubt they are using up all that much space (in comparison to your stuff) - and if you are running out of space - that is a different issue; one not best resolved by removing updates/patches.  :-)

Do not remove those through Add or Remove Programs.  That would be, at best, unwise.  Unless you uninstall the products the updates are for, do not remove the updates (the updates would be removed automatically when you removed the product they patched.)

Want to cleanup and get that machine running better?  Here are some suggestions that *will* assist you.

Do some house cleaning and dust off that hard drive:

You may wish to free up some disk space (will also aid in getting rid of things you do not utilize) by going through these steps:

Windows XP should take between 4.5 and 9GB *with* an Office suite, Photo Editing software, alternative Internet browser(s), various Internet plugins and a host of other things installed.

If you are comfortable with the stability of your system, you can delete the uninstall files for the patches that Windows XP has installed...
http://www3.telus.net/dandemar/spack.htm
( Particularly of interest here - #4 )
( Alternative: http://www.dougknox.com/xp/utils/xp_hotfix_backup.htm )

You can run Disk Cleanup - built into Windows XP - to erase all but your latest restore point and cleanup even more "loose files"..

How to use Disk Cleanup
http://support.microsoft.com/kb/310312

You can turn off hibernation if it is on and you don't use it..

When you hibernate your computer, Windows saves the contents of the system's memory to the hiberfil.sys file. As a result, the size of the hiberfil.sys file will always equal the amount of physical memory in your system. If you don't use the hibernate feature and want to recapture the space that Windows uses for the hiberfil.sys file, perform the following steps:

- Start the Control Panel Power Options applet (go to Start, Settings, Control Panel, and click Power Options).
- Select the Hibernate tab, clear the "Enable hibernation" check box, then click OK; although you might think otherwise, selecting Never under the "System hibernates" option on the Power Schemes tab doesn't delete the hiberfil.sys file.
- Windows will remove the "System hibernates" option from the Power Schemes tab and delete the hiberfil.sys file.

You can control how much space your System Restore can use...

1. Click Start, right-click My Computer, and then click Properties.
2. Click the System Restore tab.
3. Highlight one of your drives (or C: if you only have one) and click on the "Settings" button.
4. Change the percentage of disk space you wish to allow.. I suggest moving the slider until you have just about 1GB (1024MB or close to that...)
5. Click OK.. Then Click OK again.

You can control how much space your Temporary Internet Files can utilize...

Empty your Temporary Internet Files and shrink the size it stores to a size between 64MB and 128MB..

- Open ONE copy of Internet Explorer.
- Select TOOLS - Internet Options.
- Under the General tab in the "Temporary Internet Files" section, do the following:
- Click on "Delete Cookies" (click OK)
- Click on "Settings" and change the "Amount of disk space to use:" to something between 64MB and 128MB. (It may be MUCH larger right now.)
- Click OK.
- Click on "Delete Files" and select to "Delete all offline contents" (the checkbox) and click OK. (If you had a LOT, this could take 2-10 minutes or more.)
- Once it is done, click OK, close Internet Explorer, re-open Internet Explorer.

You can use an application that scans your system for log files and temporary files and use that to get rid of those:

Ccleaner (Free!)
http://www.ccleaner.com/
( just the disk cleanup - don't play with the registry part for now )

Other ways to free up space..

SequoiaView
http://www.win.tue.nl/sequoiaview/

JDiskReport
http://www.jgoodies.com/freeware/jdiskreport/index.html

Those can help you visually discover where all the space is being used.  Then you can determine what to do.

After that - you will want to check for any physical errors and arrange everything for efficient access"

CHKDSK
How to scan your disks for errors
* will take time and a reboot.

Defragment
How to Defragment your hard drives
* will take time

Cleanup the Update Components on your Windows XP machine

While likely not 100% necessary - it is probably a good idea at this time to make sure you continue getting the updates you need.  This will help you make sure your update system is ready to do this for you.

Download and run the MSRT manually:
http://www.microsoft.com/security/malwareremove/default.mspx
(Skip the details and download the tool, download and save to your desktop, run it.)

Reboot.

Download/Install the latest Windows Installer (for your OS):
( Windows XP 32-bit : WindowsXP-KB942288-v3-x86.exe )
(Download and save it to your desktop, run it.)

Reboot.

and...

Download the latest version of the Windows Update agent from here (x86):
http://go.microsoft.com/fwlink/?LinkID=91237
.... and save it to the root of your C:\ drive. After saving it to the root of the C:\ drive, do the following:

Close all Internet Explorer windows and other applications.

Start button --> RUN and type in:
%SystemDrive%\windowsupdateagent30-x86.exe /WUFORCE
--> Click OK.

(If asked, select "Run".) --> Click on NEXT --> Select "I agree" and click on NEXT --> When it finishes installing, click on "Finish"...

Reboot.

Now reset your Windows Update Components with this FixIt (you will *NOT* use the aggressive version):
How do I reset Windows Update components?

Reboot.

Check for malware:

Download, install, run, update and perform full system scans with the following two applications:

• MalwareBytes (FREE)
• SuperAntiSpyware (FREE)

Removing everything they find.  Rebooting when needed.  (You can uninstall one or both when done.)

Then perform an online scan with the eSet Online Scanner.

The less you have running all the time, the better the things you want to run will perform:

Use Autoruns to figure out what all is starting up when your computer does/when you log on.  Look up anything you do not know about using Google (and/or ask here.)  You can hopefully figure out if there are things starting when you computer does (or you logon) that you do not need and then configure them (via their own built-in mechanisms is the preferred method) so they do not start up - using your resources without reason.

You can download and utilize Process Explorer to see exactly what is taking up your processor/CPU time and memory.  This can help you recognize applications you might want to look into alternatives for and/or get rid of all together.

Now that your system is generally free of malware (assuming you have an AntiVirus application),  you have cleaned up the 'extra applications' that might be running and taking up your valuable memory and processor, you have cleared out some valuable drive space and made sure there are no issues with the drive itself and your Windows Update components are updated and should be working in top shape - there is only one other thing you may wish to do:

Obtain and install the latest hardware device drivers for your system from the system/hardware manufacturers' support and/or download web site.

If you wish, come back and let us know a little more information about your system - in particular the Make/Model of the system you have - and perhaps someone here can point you to the right place(s) to go to accomplish this.  This is not 100% necessary - but I would bet that you would gain some performance and features by doing this part.