The X-factor: Rent's rating. If it's done halfway the way it should be, it'll be rated R, while Phantom was PG-13, as was Chicago. The number one moviegoing audience - and the one that any movie needs to be a hit, especially Rent - is 13-17 year olds. If those kids want to see it, most of them will find a way, one way or another, but those that take heed to the ratings may cost Rent some $$.
BTW, if all goes well, Rent could very well make WAY more money than Chicago made, and might even pull out an Oscar or two. Will it? I think it will be fairly successful, weather or not it's really good, but as much as Chicago? I wouldn't bet against it, but I won't say it will, either. More than Phantom? Probably.
Another X-factor (a "Y-factor", I guess) is The Producers. However, if Rent is still box office relevent by the time The Producers is released, then it probably has already done a good job.
Hey, when does The Producers trailer come out?
"Who is Stephen Sondheim?" -roninjoey
"The man who wishes he had written Phantom of the Opera!" - SueleenGay
GO CARDINALS!!!