If you are having issues with your computer running sluggish the best answer so far is to use ctrl+alt+del and click on the processes tab. sort by processor usage by clicking on the tab at the top of the numbers. You will see numbers between 0-99 whichever one takes the most is your hog. You can then trace from there to what that exe is running.

Aside from that never hurts to run a adware spyware scan and a trojan detector like a squred.

You can check your startup items by going to start, run, typing msconfig, and clicking on the startup tab. Just dont tamper with anything you dont know how to use. In the startup tab simply unchecking things will let you turn them off so they dont start next time you reboot your system.