no, neither of those sites are legal. Burning a copy of a cd and giving it to your friend isn't legal either. There isn't a very great way to get around paying for music. Ruckus pays for it with ads, which is a pretty cool idea but theres all kinds of DRM on the files.
try soulseek (slsknet.com) I got like half of my library from there and my computer hasn't crashed from anything I got off there. So much music too, underground, mainstream, and obscure stuff.
Make sure you use good virus protection in conjunction with Limewire because it can be virus city.
Both of my experiences with Limewire resulted in a reformatting of the computer in the following months. Limewire can be good if your smart and careful about it, but I personally recommend safer options.