Cannot download itunes songs

Hello,
I have a Dell inspiron 1525 laptop and I have vista. My problem is that I have updated itunes 8 and ever since I have problems downloading songs. It would show downloaded for hours and still not complete the download. I have talked with tech support and even called them on the phone. Still I do not have the problem solved. I do not get an error and when I stop the download it puts the song on my documents and not itunes and the song is half completed. I even tried to leave the computer on for 24 hrs and still come up with the same problem. Any Suggestions?