Increasing Hard Disk Space in Raid 5 Conguration

I have a Dell PowerEdge Server with 3 X 146GB Disks and 1 x 300GB Disk. RAID 5 is configured on the HARD DISK.
I C:\ – 11GB & D:\ – 396GB drives presently i am running out of space on the C:\ drive and i need to increase to the size.

Please can someone tell me how to do this with the RAID 5 configuration on it and not affection the data already store or installed softwares.