^ There is no need to shout.
For the OP - there are 2 possibilities
First, If you want to ensure that in the event of one HDD crashing, your data is safe on HDD2 - This is possible by 2 means, either use software RAID onboard your motherboard, else use dynamic disks and make mirrors. This ensures that if your OS or even one HDD goes kaput, you can safeguard your data. This is equivalent to RAID1.
Second - you are no IT pro, and might have Windows crashing or not booting, and you dont want to wait for the support technician to come. In such case, you can have a second OS or copy of Windows installed, so that no time is lost. Again, this can be done in 2 ways, with the boot loader on the first HDD or both disks are independent. With the first method, if the MBR gets corrupt, then you still wont be able to boot, so I would recommend option 2.
Now, its upto you to decide course of action!