Partition of c drive beyond shrink limit

Hello,

I have Dell inspiron 5520, with 8gb ram and 1TB hdd.

when i bought, hard disk has single partition C drive alone with windows 7 Home Premium.

when i tried to partition initially without storing any data, only 600gb is available for shrinking.

I left the remaining 400gb in C drive itself. I was using as it is for a year. Now i need more space and want to partition C drive, as 350 gb space is available in that. I didn't get a Windows 7 installation CD with device.

If i reinstalled OS using Dell Data Safe and Local backup, will my whole hard drive gets wiped? or only C drive is erased?

what are the methods now i have, in order to partition C drive.?

Thanks.