Troubleshooting Hard Drive

[Plazek]

So, I am upgrading my PC and selling my old bits to my mum. Her PC died a year or so ago apparantly it was the motherboard.
I need to see if the old harddrive and everything works, but I do not particularly want to take my system apart un-necessarily.

IF I left all my stuff in the case, unplugged my HD then put the old one in, could anything major go wrong? Am I right in thinking when I take the old one back off and my one back on everything will be as it was?

Thanks

 

[semi-pro waster]

If you are just swapping the drives around to test one then replacing your original drive as it was nothing should have changed.

 

[Plazek]

Thanks a lot that is what I thought, but i don't trust myself.