Even easier: upgrade to a hybrid drive. I just did this on my iMac, and it's ... sweeet. Performance is notably quicker, and there's no changes to be done. Specifically, I had a 1TB Seagate drive (original) in a late 2009 iMac. That drive failed earlier this year; as it was failing, I copied it with SuperDuper to an external hybrid Seagate 4TB drive. I then ran on the external drive until I had time to install it per the drive replacement iFixit article.
And yes, up and running and fast. Loving it. Huge capacity without the premium for an SSD.