2 hard drives one computer, 2 different people

i have 2 hard drives... one internal and the other as a removable hard drives (in the 5.25" bay). what ive been trying to do was to get an individual o/s on each one becaus one is my hard drive and the other belongs to my wife. how would i go about doing this???? please help....

 

I would just use the Internal HDD & set up dual boot PC.
The external just use for storage, can also set up multiple partitions on it too!
Format the internal HDD with two primary partitions, load windows to each partition, you need to load all drivers etc to each,its like having two PC's in the same box.
When the PC boots you can choose which windows install/partiton to boot from, it will defalut to the one of your choice but you do have the option to boot to the other OS during the boot & you can set the time for your choice, default is 30 sec. (all options can be changed easy)
You can even use two different OS or the same, if different OS load the oldest version of windows first on the first partition.

I believe if you load windows on two different HDD's you'll have to access bios before you could boot to the other HDD or each time you boot to a different HDD, then the other thing does your pc have the ability to boot to external HDD?

I run two dual boot PC's both also have dual monitor's, I love it!