New PC But Want To Add Old PC HDD And Dual Boot

Hi, I believe I can ask questions about anything to do with online, computers etc. as well as Wordpress so, that being the case, here goes.

I am taking delivery of a brand new PC but all of my programs are on my old HDD. How do I add the old HDD to the new PC so that I can dual boot, Win 7 OS x2, one on each HDD?

Thank you,