Can't do any windows updates or SP2.

I have a Vostro 1500 running vista. I am still using SP1 as it won't let me update to SP2.

I am also unable to do any windows updates, they all come up with an error downloading and tell me to do them individually which I do but they still won't update.

I have had the laptop for about teo and a half years and this has been happening for almost a year now.