How to format an HD with an OS already installed?

[redness]

I only have an SSD right now as a boot drive with my OS installed. I need an HDD for storage so I asked a friend and he gave me one but with an OS already installed. Questions:

-What happens if I have both installed in my system and boot it?
-How do I format the HDD my friend gave me?

 

[Sharpienero]

First question answer: Whichever is set with boot priority.
Second: Use an install disc (I always use window) and format it via that.

 

[jsmithepa]

1. You cannot boot from somebody else's OS. If he has an IDENTICAL machine as yours, maybe.
2. Storage Management under Windows. If he has a recovery partition, this is a good time to obliterate it.

 

[redness]

Okay so if I power it and it boots to my SSD, will my friend's HDD show up in My Computer?

 

[jsmithepa]

Okay so if I power it and it boots to my SSD, will my friend's HDD show up in My Computer?

It will show up as the next available drive letter, D: (?)

 

[redness]

Okay so if I power it and it boots to my SSD, will my friend's HDD show up in My Computer?

It will show up as the next available drive letter, D: (?)

Can I just use it as a storage then without having to reformat it?

 

[jsmithepa]

Can I just use it as a storage then without having to reformat it?

You don't have to do anything, if you don't mind having your friend's craps there taking up space.