Clone HDD internally?

Forgive me if this isn't in exactly the right place, or if I overlooked a similar thread.
I want to clone my hard drive, or perhaps I'm using the wrong term.
I have a 500GB HDD with Win 7 installed. There are a couple of partitions and user profiles for the family. I also have a 750GB HDD (currently empty). These are both installed internally in my desktop. I do not have an external enclosure.
I want to use the larger, empty HDD to make an exact copy of my existing drive so that if it crashes I can simply remove the dead one and reboot from the newer drive.
I do not want images that need to be restored or incremental back-ups. I do not want to purchase an external enclosure, but I am willing to remove the 2nd internal drive after the backup is made (just in case that's an option). I'd prefer free software if there is a good option, but I'm willing to purchase the right software for the job if it does what I want with as little hassle as possible.
Can anyone help me?