Today I had to convert my external disk form FAT32 to NTFS. I was confronted with the problem that an ISO file was 9GB and FAT32 couldn't handle that.
Convert is a tool that is part of your Windows OS.
Here is the syntax to convert the disk:
>convert diskletter: /fs:NTFS [enter]
After starting the convert tool you'll have to enter the disk label and the conversion starts. First it checks the disk for errors and than the actual conversion starts.