Downloading -legal or illegal?

Watching this film forced me to ask again the question which I have asked many times so far. I have discussed it through with my family, friends, teachers  etc. but we  have still not found any common answer. I will try to present some statements considering this issue in this paper and I encourage you to leave your thoughts in the comments.

I would like to concentrate on the problem of sharing and downloading music from the Internet. There is a lot of Polish Websites where you can place and save the music for free. Is it legal? The Polish law says: YES. But there are some conditions. According to uploading: you are obliged to have all rights to the file which you are making accessible. According to downloading: you can do it only for your own use and you cannot share it with others. The problem is that the P2P downloading requires sharing so P2P downloading is against the law.

Well, why cannot I make an access to the files which I have downloaded? If it was the CD I could lend it  anyone and it would be legal, would not it?  
[You can find opinions of other internet users here.]
Moreover, when someone recorded the music and the file is commonly accessible why cannot I help others to find it? I agree that most of musicians want to earn and I respect it. However, what is the difference if someone downloads by oneself or with help? For the case of musician’s money there is no difference though. 

What could be more danger in this case is when you publish your own music file because there is a chance of property theft. I mean that someone can use your file (e.g. record it by oneself and say that it is his or her composition).

For example, I published one of my songs in the Net. The main reason was to smooth the way of listening it for my friends. However, I am not against listening it by others. However, I would be angry if someone recorded it again and published as his own.

According to the problem of downloading: why could  I not download the song which I can listen to on the radio even on the internet radio? Few years ago I could go to the shop to buy the tape, listen to the radio and push "record" when my favorite song appeared. What is the difference between those old way of collecting good music and the way of today?

I have to admit that this questions seem to be without the answers. Although the law says something about it, although the conscience says something else, the problem is to understand every voice in this discussion. It seems  that every voice is different and there is no rule who says NO to such business and who says YES.