I want to update the IIS server from 5.0 to 6.0 or higher.
The condition is that I cant upgrade the server. My machine is Windows XP SP3
Is there any way I can only update the IIS.
You can install IIS Express 7.5 on Windows XP. Note that the Express version is a lightweight (yet fully featured) version of IIS meant for development purposes, not production hosting. You shouldn't use Windows XP as a production server anyway.