Replacing An Internal HD In A Desktop?

I have a three yr old hp Pavillion desktop. HD has totally conked out. Was going to just get a new one, but was wondering about the feasibility, and ease, of just replacing the HD. What am I letting myself In for ?

It looks like it will cost me around $ 100 to buy a new drive, so it will be a pricey experiment if it does not work out. Lost a lot of the paperwork, so am not fully sure as to what,is in it now. I looked inside, and apparently it is a Seagate 1 TB drive. 7200 rpm. SATA, 3 GB/sec

Has the dimensions of approx. width of 4 inches and depth of 6 inches. Is this what is called a 3-1/2 inch drive ? So, what do you think ? Worth a try ?

Will the electronics in this 3 yr old pc support a new hd with its built in new electronics O.K. ?

If I decide to try just replacing the drive, what should I buy ? What should I be aware of In regards to buying a hd for my old pc ? And, do they come pre-formatted ? If not how is this handled ?

Are there still master-slave jumpers that need to be set on the new hd ? After installation, do,I just run the "Restore" disk set of 3 disks to get Windows 7 on it again ? Do these restore disks that I created when I first got the pc have Windows 7 already on it ?

Not all that sharp with this stuff, but am a retired Engr., so reasonably comfortable with this kind of thing. Still, I would not really want to dump $100 if there are lots of potential pitfalls and caveats I am not considering.