Can you put hot water in cold water?
I hate people who answer questions this way.
Can you go drown yourself?
so can I just turn off my computer, plug it in with SATA and the Power Supply, and just turn it on and see it mounted :S?
Yeah, it should be fine. But if you want to set up a RAID array or something more complicated, you might need additional hardware like a RAID card or something. If you're just going to use it as a backup drive or extra storage, you should be fine as is.