It might do, but I must confess I've never been involved with the setting up of servers, so please don't consider me an authority on the issue
However, IIS is Microsoft's system and is probably better suited to using ASP (Active server Pages), so an Apache server may be the better option for you since it seems that most PHP sites I've come across are run on Apache platforms.
Certainly that seems to be my experience: IIS -> ASP; Apache -> PHP.
But IIS can support PHP (as you know); it may be that there is a setting somewhere that prevents/adversely affects those huge uploads from working on an IIS system that wouldn't be an issue on an Apache server.
