Is it possible without having to reinstall windows?
You should try some virtualization software like vmware, virtual box or other of that type, then install Linux on it.
If you are looking to create a dual boot environment, Linux distros usually have a partitioning too that should allow you to resize the Windows partition to make room for a Linux partition to exist. I know for a fact Ubuntu has such a tool and I have used it with success.
Thanks. Could you tell me if I were to stick another HD in there and set it as a slave, could I install Ubuntu on that HD and still have a DB option?
Absolutely. That is an option.