I recently updated both hard drives in my two new Dell computers. I did a mirror imaging of both with the included software included with the new drives. Worked perfectly. I took out the old hard drives and put them into my bedroom dresser drawer for that rainy day. I use a flash drive to save my data files. The new hard drives booted up normally and have worked fine for the past three months. Piece of cake.
I only keep one hard drive in my computers and have a single connection cable in order to improve the air flow since each are the IDE cables. The new SATA drives wouldn't be a problem. And it also puts less strain on the power supply.
Just for the record. Microsoft regards the motherboard as the "real" computer, not the hard drives. The hard drive is married to the motherboard. You can't just stick a hard drive in one computer from another computer and expect it to work properly. I learned this myself when the hard drive would not work in my wife's Dell 2400 from my 4600, and vice versa. Yet both have the exact same model hard drive. So the mirror imaging will have to be done for each individual computer. Takes a couple of hours or so.
If the motherboard would ever fail or need to be replaced I would have to talk Microsoft into allowing me to transfer the operating system and software as it came preconfigured on each Dell which is why I purchased them being cheaper buying both computer and software together.