Shrinking C partition problem

I have a 100GB HDD with 2 partitions. C has Vista Ultimate installed and D
is for Windows recovery. I want to pull some space out of C for another
partition for a dual boot option. I have had horrible luck with 3rd party
software, including GPart (the GUI won't load). The built-in tool will only
shrink C by 1.81GB. I need at least 10GB for the other OS, preferably 15GB.

Also, when I create the new partition from the unallocated space, I am not
able to expand it. Anybody have any suggestion?

[Sazxda]

Pls visit
YouTube - How to Partition a Hard Drive
i hope so u find ur answer