Regarding hard-drive and Windows 7

I have 2 hard-drives. As followed:

I have Windows Vista on my C drive and my D drive, as you can see, is empty.
I would like to test Windows 7 on my system, so could i install it onto the D drive and choose everytime i start up my computer, which hard-drive i want to run from? (I’m hopeless with computers)
Answer #1

http://www.techspot.com/guides/143-dual-boot-windows7/

Answer #2
Thanks alot, really helpful