is there a prograhmn which can take the name of my mp3 and rename it to the format "artist-song title"

Yes, a tag editor such as -
http://www.magnusbrading.com/mp3ts/

or read this for more -
http://forums.winamp.com/showthread.php?threadid=21147

or you can work something out with Irfan view, just press b on the main window and check the batch rename radio button and modify the options to your taste or something.

Somebody should write a plug-in for WA3 that batch file renames your mp3's. That's be very cool.

sig says it all.