Just purchased the 27" Retina iMac with Yosemite I have 2 MBP's I am about to wipe clean, one I am adding a SSD drive to and both being set up new again but I know I can't set up Yosemite on either one. 1) Late 2009 MBP presently on 126.96.36.199. Have original Snow Leopard Disc for it but wish to put on a later OS but one that is free as i don't wish to put any money into this MBP. My present DVD drive in it is toast but I do have a USB mac trackpad, albeit not yet opened I could use with it. I'd prefer IF possible, to have an OS i can download and put on a USB key but i am not sure which OS I should put on it using this method that i won't have to buy. You guys all know far more than I. What OS can I use for it using what I have explained above please??? 2) is a late fall 2011 MBP. I have read numerous problems for people with this particular MBP that have upgraded to Yosemite so I am still on 188.8.131.52 as well. Same question, is there an OS that I can download and place on a USB stick I not need to pay for other than Yosemite that I can place on this MBP? (I haven't yet decided if I should do it before or after that SSD installation?) Thanks in Advance..