|""1-Does the second hard drive show up in the mboard's bios Setup?""|
"...the controller card is PCI with SATA connection and both drivers are connected to it."
OK, then there is probably no problem regarding the drives, the controller, or the drive's connections to the controller.
If there were, you would probably be getting an error message related to the RAID array, probably every time you booted the computer.
The way your RAID array is set up, the operating system sees the partition(s) on both drives as being on one 72gb drive. If you made the RAID array use the max allowable amount of drive space, the operating system sees the two drives as one 72gb drive, minus whatever space is taken up by the RAID array formatting, and minus the space taken up by the operating system partitioning and formatting. There is no unallocated space left with which you can make a D partition.
I haven't used any type of RAID myself, but in theory, I would think that if you re-made the RAID array so you did NOT use the entire space on both drives, the remaining space would be seen as the D partition in the operating system, if you could make a second partition with the RAID array set up, or you could make a D and an E partition with the operating system, if you can leave that remaining space un-allocated in the RAID array set up. If not, I would think you would need a third hard drive.
RAID-1: This type is also known as disk mirroring and consists of at least two drives that duplicate the storage of data.
RAID-3: This type uses striping and dedicates one drive to storing parity information. The embedded error checking (ECC) information is used to detect errors.
RAID-10: Combining RAID-0 and RAID-1 is often referred to as RAID-10, which offers higher performance than RAID-1 but at much higher cost. There are two subtypes: In RAID-0+1, data is organized as stripes across multiple disks, and then the striped disk sets are mirrored.
In RAID-1+0, the data is mirrored and the mirrors are striped.
RAID 1 (mirrored settings/disks) could be described as a real-time backup solution. Two (or more) disks each store exactly the same data, at the same time, and at all times. Data is not lost as long as one disk survives. Total capacity of the array is simply the capacity of one disk. At any given instant, each disk in the array is simply identical to every other disk in the array.
RAID combines two or more physical hard disks into a single logical unit by using either special hardware or software. Hardware solutions often are designed to present themselves to the attached system as a single hard drive, so that the operating system would be unaware of the technical workings. For example, you might configure a 1TB RAID 5 array using three 500GB hard drives in hardware RAID, the operating system would simply be presented with a "single" 1TB disk. Software solutions are typically implemented in the operating system and would present the RAID drive as a single drive to applications running upon the operating system.
There are three key concepts in RAID: mirroring, the copying of data to more than one disk; striping, the splitting of data across more than one disk; and error correction, where redundant data is stored to allow problems to be detected and possibly fixed (known as fault tolerance).