Hubby's HP Pavilion Process so Slow

I should normally be using hubby's HP Pavilion laptop with Vista program but it is just processing very very slow. Imagine sometimes when I open it, it took me an hour or two to do that. Sometimes it just makes me feel so mad. Sorry to say that. Honestly folks, I am not a computer expert. That is also the reason why I am asking the experts out there what are probably the reasons why it is processing so slow. I also want to surf it online why it is acting like that. I also appreciate any information from the experts out there. Thanks in advance!