Got the 500GB Roamio 3+ months ago and I only record things in standard definition but I almost run out of room. Just curious if I remove the original HDD, put a new HDD then maybe 6 months from now I wanted to view an old show again on the original HDD, can I take out the replacement HDD, put back the original and the shows will be there to watch again? Also which HDDs would you guys recommend? I want at least a 3TB drive that is on sale/good price right now. And is there a video on other instructions on how to take the HDD out? Thanks!