Reformatting or resetting to factory fresh for dell 17r?

Had my Dell 17 R about 2 months now but seem to have got some sort of malware on it, everything is loading in super slow motion, and I keep getting those download anti virus pop ups coming up. I'm using windows 7, but I notice Dell no longer uses Symantecs system reformat software thet they used to. Now obviously i dont want to fk it up so I want the best way to get it back to its factory fresh settings. How do you reformat now?? With my old Dell Inspiron 1700 it was soo easy to do but now it seems so friggin complicated. Any ideas??