sikhfella88-
press CONTROL+SHIFT+ESCAPE all at once to open the task manager. select the tab labeled processes, and click the header in the CPU column, thus sorting your processes by thier cpu usage. reply which processes are generally taking up the most CPU usage, and give thier percentages.
before you go off and do that, answer me this: does this machine have any antivirus software/protective firewall? if not, then i reccomend AVG free edition (free.grisoft.com) and sygate personal firewall. failure to use said software could easily result in malicious software bogging down your system.