I have just bought HP laptop with Windows 7 (64 bit). It has 500 GB HDD with three partitions: small hidden system partition, 12 GiB HP recovery partition, and 450 GiB C: boot partition.

I would like to split this large C: partition into two partitions, leaving only 100 GiB for system, and giving the rest to new data partition.

Although Windows built-in Disk Management utility has an option to shrink the bootable partition, it only allows me to shrink it roughly by half, even though only 20 GiB on the partition is used. As far as I understand, system unmovable files lie in the middle of the partition, preventing Disk Management utility to do what I want.

And since new HP laptops don't come with OS installation disks (they only allow you to create recovery disks youself), I can't just repartition HDD and then reinstall OS.

So, is there any way to shrink C: bootable partition and preserve Windows 7 working?

P.S.: I have tried to use 3rd party GParted utility, and after shrinking the partition Windows 7 stopped booting with BSOD. System recovery didn't work, and I had to do factory recover. Since this is a long process, I would like to avoid doing it again :) So, please, suggest only proven solutions.