I have not read much about the "non-purchace" entry form on Apple's site. It says you can enter 25 times a day, but how will this give you a chance to win if it is based on the person who downloads the 10 billionth song? Is it worth entering 25 times a day on their site?
It really isn't. This part of the rules confuses most people.
There is no reason to enter into the contest yet. It's whoever downloads the 10 billionth song, or whoever enters without purchase after the 9,999,999,999 song download.
The limit seems to be implemented to confuse people into believing they get 25 chances to win per day. There will be no drawing, except for simultaneous downloads.
Also, non-purchase entries do not affect the counter. The count is only of songs.
I don't understand why Apple would implement these rules, but I'm sure they have their reasons. Also, if you enter 25 times on the day of the 9,999,999,999 download before it is time, you cannot win unless you download a song.