Why is my computer so slow?

I installed XP Pro on my Windows box a couple of weeks ago. I’ve managed to de-uglify it but my main problem is that my machine, which ran perfectly quickly under Win2K, now crawls. It’s not the newest machine in the world (Athlon 1.4/768MB RAM) but it should be able to handle XP … I would have thought so anyway.

Word hangs for a couple of seconds every few minutes, Eudora takes an age to process mail, I’m starting to thnk that I’m going to have to go back to Win2K just to get some work done. Any ideas on what might be up with the thing gratefully accepted …