If i delete stuff will my pc speed up?

You need to stop programs starting up in the background every time you start your PC - you don't know they're running, but they are. Click Start->Run then type msconfig and go to the Start Up tab. Untick everything except your virus scanner and OK it. You'll probably need to restart. This will stop all those programs starting up every time you start your PC - in the vast majority of cases, that is what's slowing down your PC.