both explorer.exe and taskmgr both spike like that, esp explorer.exe. view any other computer's cpu usage and you will see similar spikes. for questions on windows issues like this I recommend shooting a pm to Mak213. it's also common for you to have several instances of explorer.exe and igfxtray.
No process should be anywhere near that unless its being heavily used, corrupt, infected with spyware/virus, etc or other system issues and sometimes low amounts of ram.