I would not use any of the speed up my pc services as found on tv. Most of them will cause more damage than good.
As far as the cisvc.exe - it is a vital part of xp and disabling it could cause many programs to not run correctly.
Have you recently installed the Windows Search 4 feature? It is possible - that if you have a large amount of data on the machine - that the indexing service is constantly running. This will continue until it completes. You can try to disable indexing and performing other tweaks to see if this speeds up your machine by following the instructions here.
If these tweaks do not help - I would be more inclined the think you may have some kind of malware infection. If the previous steps did not help you - Please visit the malware
forum and follow the instructions at the top. Start with the instructions HERE!
These self-help tools will help you clean up 70% of problems on your own.
If at the end you are still experiencing a slow machine come back to this section
and well see what else could be the root of the issue.
Edited by geekhelp4u, 01 November 2009 - 09:33 AM.