Provided by Microsoft Support, a step-by-step guide on how to create a partition on Windows Vista or Windows 7. As described:
We received a call: The system is installed on my machine. But there's only one partition. I don't want to reinstall the system to re-partition. Is it possible to create another partition?
This might be a problem that troubles many users. Generally, some third party software can provide such features. However, now Windows Vista/Windows 7 enables you to make some certain degree of adjustments towards current partition sizes.
If a drive ever has a corrupted format it essentially just becomes a RAW volume/partition, which can be seen when booting up Linux (live CD if you want). That's what I do if I ever need the files and can't access it with Windows. Then you can completely reformat, otherwise shrink format and extend in the methods that they're doing there.