I apologize for the long post. I tried to be specific and clear. Currently I have a mid-2011 iMac, 2.7 ghz i5, 1TB 7200 rpm, 4 gig RAM and an external 1TB Seagate goFlex portable drive with the Thunderbolt adapter add on which is my Time Machine backup drive. I'm using OS 10.6.8 Snow Leopard. My HD is about half full. I'm not ready to upgrade to Maverick yet since it is still a very new OS. What is the best way to be able to use my current programs with an updated OS and a new SSD with HD as basically my storage drive and continue to use Time Machine on my external portable? I want to add an internal SSD 256 gig (probably a Crucial M500). I have built desktops and have the skills to do this with the help of watching youtube video installs. The SSD will be my boot drive and used for several programs currently installed on my HD such as Adobe Creative Suite, Word suite, a few games, and video editing. All this is currently backed up on Time Machine. This is where I need advice. I want to upgrade to Mountain Lion. Should I upgrade the OS on the HD first, then install the SSD? If this is the case will Time Machine be able to transfer the OS and programs I want to the SSD? or should I install the SSD then do a clean install of the new OS on it? If so, will the "new" Time machine be able to transfer the programs I want to the SSD? Would I have to do a new complete backup before the transfer with the "new" Time Machine? I no longer have some of the program disks and do not want to lose the programs. or does it matter which way? Is one better than the other? Or is there a better/easier way to accomplish my goal? Thanks for your help in advance!