Can I play downloaded songs from my PC on my iPhone?

I'm thinking about getting an iPhone 4 and i was wondering if the iPhone can even play all the music I have in my library on my Laptop or Desktop, OR will the iPhone ONLY play songs that come directly from iTunes? If so, then i can't put my all the songs on my computers to my iPhone. Is this right?

Yes it should work

If what you want to know is will the iphone play the music you illegally download, the answer is yes. Just put it in your itunes library and sync it. It will however only play.mp3 and.acc, so if your songs are for example.wma, they'll need to be converted 9but i think itunes will do this for you.

Ok you can but you need to add the songs into itunes.go to music-itunes-itunes media- automaticly add to itunes.place all your music there and it will show in itunes and you can sync them into your iphone
the only dis advantage i've had is when i hold the iphone at the top i get a decrease in signal. But thats cause i'm covering the antennae