I want to by my 9 year old an Xbox 360 for Christmas. What's the difference arcade/elite?

I know it's October, but he has been wanting it, and it's too expensive for me to afford, but I will for xmas. On xbox sire elite is $299., arcade is $199. We have a WII, but there is a particular game (not the only reason, lol) that they only make for xbox 360 that he wants. Is it really worth an xtra hundred bux to get an elite? I could use all the help you are willing to give here.