Don't get Limewire. Get Frostwire
http://www.frostwire.com/
Or better yet, if you are only downloading YouTube videos and music download this
http://download.cnet.com/YouTube-Downloader/3000-2071_4-10647340.html
You just take the URL and paste it into the box and click download.
It's an MP4 once you download and you just click the convert button, find the file, and put it on MP3 if you want it as that. Glad to help.