I have come to the conclusion that windows (and vista in particular) in not a good tool for formatting or partitioning drives. I like to use a tool provided with Linux called GParted. You do not have to install Linux to use this tool. Linix is available as a "live CD" which means you can run it directly from the CD without installing anything on your harddrive.
I don't know how comfortable you feel with trying this. Perhaps you would prefer to wait for other suggestions for doing this within Windows? If you want more detailed instructions for the GParted option I will provide what help I can. (Another advantage of GParted is that formatting is quick)