Swap HD from one TivoHD to another

Can I safely and simply swap the HDD from my current TivoHD to a different TivoHD that I buy on ebay?

The HDD that I have now is an aftermarket one.

Will it be as simple as taking the drive out of one and putting into the other? Or will there be any configuration changes that I'd have to make? (like the HDD isn't paired with the TivoHD that it is in, is it?)

Thanks!