Debbie,
Check out the Castle Doctrine law for Ohio:
http://www.buckeyefirearms.org/node/5753
In states which have adopted this type of law, the line is a bit more clear.
I agree with others, you're not necessarily trying to shoot to kill, you are shooting to stop. Most of us, even though we would like to think otherwise, are not good enough shots or skilled enough in high stress situations to try and shoot someone in the leg or arm.
Your best bet is to aim center mass of the torso. It is your biggest target area. A well placed shot from most self defence rounds (9MM HP, 38+p, 357, 45, etc.) is going to stop or severely slow down an attacker. Everything I have learned in various training classes is if you have to shoot, shoot until the thread is stopped. It's not so much about trying to kill the intruder or trying not to kill the intruder. It is about stopping the threat to you or your family. If the intruder happens to expire before help arrives, it was not his lucky day.
On a practical basis, I would have difficulty shooting someone over "stuff". There is no stuff in my house worth killing someone over. On the other hand, I could use deadly force to stop a threat to myself or my family.
I pray I will never be faced with that situation. I've never shot anyone and pray that I live the rest of the days God has allotted for me in this life being able to say the same thing. Even though I own firearms (several Rugers by the way), I have no desire in this life or any other to use one against another human being.
Sounds like you didn't get hurt on the trade. The guy at the shop got something he wanted, you got something you wanted. You are both happy with the deal, that is the markings of a fair trade.
If you haven't shot a lot, remember, practice, practice, practice. Get to know your firearm like an old friend. Learn how it functions, how to clear the weapon if it malfunctions, how to field strip it, clean it and put it back together.
ALWAYS AND I MEAN ALWAYS check the magazine and clear the chamber before you decide to dry fire or field strip the firearm. Make absolutely sure (double check if necessary) it is unloaded before any operations with the gun.
This may be old news, but I do not know how much experience around firearms you may have. If you have a lot of experience, then this was not meant for you but someone else who may read the thread.
Jeff