When it comes to full read and write support for windows drives, OS X can only do so on FAT32-formatted partitions. The newer and popular NTFS format is a more stable option for Bootcamp and other applications; however, it is only readable by OS X. One of Apple's selling points for OS X is the enhanced Windows compatibility, but the lack of write ability to NTFS drives makes transferring files between the Mac OS and Bootcamp rather cumbersome. Luckily, third-party utilities enable this missing feature.
There are two popular options for gaining full NTFS support in OS X. The first is Paragon NTFS for Mac OS X, and the second is the open source "NTFS-3G" package. These packages are simple to use, in that you just install them and should then be able to both read and write to NTFS drives.
This is the commercial option for NTFS support, which has the benefit of being supported by a company so you have someone to gripe to if things do not work.
This is the free option, which has worked quite well for myself and others; however, being an open-source project it is available for you to use at your own risk. The "MacFUSE" package is used by NTFS-3G, and installs support for a variety of third-party file systems in addition to NTFS. It is a free filesystem suite that bundles together open source projects such as NTFS-3G along with others to create a one-stop shop for being able to read and write to natively unsupported filesystems in OS X.