Have you done a HDD clean up and defrag??

Have you installed any new programs over the last few weeks before this problem started??

How full is your HDD?? A full HDD has a tendency to run slower.

How old is your setup?? I personally fdisk, reformat & reinstall at least once a year. Yes this is with XP, too. I think of it as changing the oil. Saved files go to my 120 GB HDD Slave. My main HDD is only 80 GB for easier handling.