What happens to my old Time Machine backups after I restore my computer data?

[iMore Question]

My parents own a 2007 iMac that up until recently, was running Snow Leopard (10.6.8) and only had 1 GB of RAM. We went to an Apple certified technician who upgraded the computer to 4 GB of RAM and also installed Mavericks (he warned us that upgrading from 10.6 to Yosemite may be too big of a jump and cause unnecessary glitches). He effectively had to reset all of our computer data in order to make this happen. I've used Migration Assistant to transfer all of our old files and information to the new-and-improved, empty iMac. My question is, what happens to my external hard drive running Time Machine now? If I configure it to this new, empty hard drive, will my three years worth of backups be erased? Or will Time Machine keep the files and pick up where the old computer left off?

 

[kch50428]

This would be an appropriate time to start fresh with TimeMachine in my opinion... All the data migration assistant moved to the refreshed iMac will once again get backed up by starting TimeMachine fresh... so there'd be no need for the old files.