If you are not using iCal or iPhoto, it will not be running as long as you properly quit the application (i.e. with iPhoto open, click on iPhoto in the menu bar and then click on 'quit'). It will not run unless you launch it again - that is how the Mac OS works and the apps won't be using any memory if they're not running. You can see what apps are open in your dock - there is a little indicator below the icon. So, if you see that, click on the icon and then quit it. And, the apps are still there - they just aren't running.
If, on the other hand, you are talking about deleting them: that is not a good idea at all to mess with apps which are part of the system. If you should do it, there is no way to get them back besides an install from the install disk.