Rather than leaving you searching to your own devices, let's start things off by getting some information!
What kind of computer are we talking about here, make and model?
What is your processor, how much RAM do you have?
How old is it?
Is the problem limited to something you do, like a certain program or programs, or is this slowness all the time?
Was there anything in particular you were doing when the problem first started?
Is your Windows XP fully up to date?
Are all your hardware drivers up to date?
If you can help by answering some and or all of that, it will give us all a good starting point! Searching our forums isn't a bad idea, but I'm kind of proactive when it comes to computers, so if you can, answer the above and we will see what happens!