Looking over your posts, we need to clarify your disk layout. Can you post a snip of your Disk Management?
Usually OEMs put the recovery partition first and the OS second. That would be from left to right in Disk Management. If your recovery partition D is on the left, then next (to the right) is your C partition. You can shrink the C partition, which will give you un-allocated space on the right side. This can then be made into a new partition.
Just so you know, there is a known issue with shrinking the C partition, sometimes it will only let you shrink it by a small amount. This can be easily overcome with a free third party disk management program.
As mentioned previously, make a backup first, it's always better to be safe than sorry. Many have recommended Windows Backup, a good free alternative is
Macrium Reflect. You can keep the backup on your C partition, better to have one there than none at all. This can be moved later if needed.
Windows Disk Manager should be able do that for you.
These Seven Forums tutorials will explain it.
How to Shrink a Partition or Volume in Windows 7
How to Create a New Partition or Volume in Windows 7
If you have any questions, just ask.