How to format a disk to NTFS using Mac OS X
OS X can default read NTFS disks, but not write to them.

Possible solutions/options:

NTFS for Mac OS X (10 Days Trial): I use this one, and it does the job very well. When the driver is installed, you format your NTFS disks with Disk Utility where you select Windows NT Filesystem as the format.

Tuxera NTFS for Mac (15 Days Trial): I haven't tried this one, but it should also do the job.