You can allocate that "free space" into it's own partition or back into your main partition using any partition management software.
My favorite is Partition Wizard.
Partition Wizard Home Edition (FREE) 
Warning
You should always backup your information/hard drive before peforming any hard drive maintenance/partitioning, even if you're simply shrinking or expanding a volume.
The process shouldn't hurt the data that's already on the hard drive, but you never know what'll happen so back up if you can.
How to resize your partition:
- Choose the main partition [C:]
- Choose resize partition (On Left)
- Resize to whatever size you wish to use, the "free space" should be available. That is, you should be able to increase the size of this partition to include the free space (given that it's on the same hard drive)
- Confirm
- Apply
How to create a new partition out of the free space
- Choose the free space.
- Choose create partition (On Left)
- Adjust slider to whatever size you wish to use.
- Confirm
- Apply
If you need a alternative to the traditional Windows Backup / System Imaging utility, I suggest that you try out Macrium Reflect Free Edition. It will allow you to create a carbon copy (image) of any drive and store that copy on an external drive. Once you've done this you must create a Linux Live CD through the software which allows you to boot via this media and then restore any partition of the required size to that image's original state.
http://www.sevenforums.com/software/...tml#post813897