XP laptop stuck in low gear....help???

Hi,

I have a laptop with XP that has become unworkable because it is always "thinking" and takes forever to access or do anything. I have MS security essentials and I need help please.

It is an oldish Dell and I just want to be able to use it to do the basics and browse remotely.

Can anyone please walk me through what I can do to clean it up and get it working to a decent standard?

thanks,
Navale