Can anyone suggest a problem that may be causing my computer to download really slowly?

I think that it may be because I have alot of video files on my computer, but I am not sure. It’s being ridiculously slow with limewire, and especially buffering videos online. Does anyone think they know why? Or can perhaps suggest a solution? Thankyou. And in case it helps my computer is a vista home basic laptop. Could this be effecting it?