Bootcamp assistant won't let me increase the Windows partition I'm trying to install Windows 7 on my Mac. The Bootcamp Assistant won't let me increase the Windows partiton's size above ~45 GB. I've got 200 GB free out of 500 GB on my SSD.

I run Disk Repair, but that didn't help. Do I have to buy iDefrag and defrag my disk, or are there other options (besides reinstalling OS X from a backup)?
I think alimack is right, has to do with contiguous space.  I resolved without purchasing idefrag.   Heres how.  In my case I had a 250gb drive and was only using about 50gb.   Boot camp was only allowing me to create a 125gb partition for windows.   I accepted that and partitioned the drive in boot camp. Before installing windows I rebooted the Mac OS, went into Disk Utilities and then deleted the windows partition.  Now start again and run bootcamp and you will find a lot more space is available for your windows partition.