Windows Help Please: high 'System' usage

My PC, which is rather old, is showing very high usage for 'System' in Task Manager.
Currently, the top 5, ordered by CPU Usage are:

1. 1:40:46 - System Idle Process
2. 1:01:41 - System
3. 0:21:35 - visiongs.exe (motion detection webcam)
4. 0:09:26 - firefox.exe
5. 0:04:38 - Smc.exe

(whereas my laptop is currently showing a couple minutes of System for over 44 hours of System Idle Process)


Any ideas what's causing this, whether I should be worried, etc?