not im not IT expert, this is extracted. 
Over time, Windows XP tends to get clogged up with extra files and
programs that can slow down your computer's performance and cause
your computer to behave strangely or even stop working altogether.
Here's how to keep Windows running smoothly.
Delete Unwanted Files and Programs
Windows Disk Cleanup Utility keeps your hard drive free of unneeded
files and programs, frees disk space, and can even speed up PC
performance.
Click Start | All Programs | Accessories | System Tools | Disk
Cleanup to start the utility.
Select the hard drive you want to clean from the pull-down menu and
click OK.
Be patient. It may take a while for Windows to scan the disk (see
Figure 1). When done, Windows displays the categories of files it
deems suitable for deletion.
Figure 1: Be patient. This box means Windows is analyzing the hard
drive.
Click a category to see a description of the selected files to be
deleted. If you want to see a list of the individual files in a
category, click View Files (see Figure 2).
Figure 2: Pick a category and click View Files to see all the files
and folders to be deleted.
Double-check to ensure you're not deleting any important files,
especially those in the Recycle Bin (see Figure 3).
Figure 3: Check the files and folders in each category before
deleting, especially those in the Recycle Bin.
Click the More Options tab to remove even more files.
When you're ready, click OK to begin the cleanup process.
Delete Unwanted Startup Programs
As you add software to your PC, the number of programs that
automatically start with Windows get bigger and bigger. You
probably don't need all these programs running all the time; they
just eat up memory and increase the chances of a software conflict.
To remove the ones you don't want:
Go to Start | Run and type msconfig in the text box shown in Figure
4. This brings up the System Configuration Utility
Figure 4: Type msconfig to start Windows' System Configuration
Utility.
Select the Startup tab. You'll see a list of all the programs that
automatically start with Windows (see Figure 5). Remove the check
in the box next to a program name, and that program won't start
with Windows.
Figure 5: Disable any programs that you don't need or don't
recognize by removing the check from the adjacent box.
Click the Enable All or Disable All buttons to do just that.
If you're unsure what a particular program does, look under Command
for the location of the program file.
Pick the programs you want to disable, or click Enable All or
Disable All to manipulate all the programs at once. Remember, you
can always start a disabled program manually from the Start | All
Programs menu or by finding the program's executable file in
Windows Explorer and double-clicking it.
Reboot your computer to compete the process.
Keep Windows Up to Date
Windows XP is a work in progress; Microsoft is constantly issuing
updates to fix bugs, security holes, and problems. Updating your
Windows files is one of the most effective ways to keep your PC
running smoothly and safe from unwanted intruders.
Click Start | Help and Support. Under Pick A Task click Keep Your
Computer Up-To-Date With Windows Update.
Windows will scan your PC and offer you two choices. Pick Express
Install to install critical updates or Custom Install to install
some or all of the available updates (see Figure 6).
Figure 6: Select Express Install for the most important Windows
updates.
Windows can automatically download updates and alert you when
they're ready to install. To enable this, go to Start | Control
Panel | System and select the Automatic Updates tab. Select
Download Updates For Me, But Let Me Choose When To Install Them
(see Figure 7).
Figure 7: Set your PC to automatically update Windows.
