How do I use my music as a ringtone (more than 30 seconds of it) on my Sony Ericsson W580?

You will need DRM Packager 1.35 and MyPhoneExplorer. To create a .dm file, install the DRM packager then drag and drop your MP3 into the window and click "Create DRM content." Plug in your W580 and put it in phone mode. Open up MyPhoneExplorer. Drag and drop the .dm file into the white window. Your phone should now have a pop up window saying that you have transferred a music file. Click yes to install it in the music folder. After it installs another pop up will ask you how you want to use it, choose "Ring tone" and you are finished. This should work for both Rogers and AT&T phones. Another alternative is to debrand your phone, which risks bricking it.