If I understand correctly, you installed Windows yourself when the system was built. If true, you can retrieve the activation code for Windows and reinstall it (if it is a Dell, HP, or another OEM PC, the activation code is probably only valid with a vendor disc). Search on “belarc advisor” (belarc.com), download it, and run it on that PC. It will give an inventory of everything including the Windows activation code. Then you will need a system disc for the same Windows version you have. People sell these on ebay and Amazon, but make sure you obtain the exact same thing. Any IT guy worth his salt has a drawerful of these discs. With the disc and code, you can reinstall Windows. If your system was OEM, you need an OEM disc; if your system was Microsoft, you need a Microsoft disc.
But before you spend any money on a disc, look at the below URL from WDC. Acronis is disk imaging software to copy a disk to a new one. I must admit, I’ve never imaged a RAID drive, but if your system is working, it should contain a complete operating system. Acronis is a free download from WDC, so you just have to invest your time. Read the instructions first. Install the new drive inside the case replacing the trashed one. However, as the moderator said, cloning a RAID drive is not the usual procedure.
http://support.wdc.com/product/downloaddetail.asp?swid=119&wdc_lang=en
