Internet won't allow me to dowload software

Hello,
I've been trying to download software such as limewire and google crome on my computer, which is a windows XP and for some reason the internet won't allow me to. I already disable the Anti-virus to see if that was the problem but still doesn't work. The Internet send me a message that my security setting won't allow me to dowload the program. I have Internet Explorer 8. Thanks any suggestions......