I've got a 2009 MacBook Pro (5,3 Core 2 Duo 4GB memory) running 10.6.8. It looks like I'm going to have to upgrade the os but the question is should I do it in one bound to 10.10 or progress to, say, 10.8 (Mountain Lion-still supported I believe) ? I don't want to cause more problems than are necessary. I know that I'll lose the ability to use any old PowerPC applications but is there any other difficulty that I should be aware of. I have an even older 2006 MacBook Pro which also runs 10.6.8 and I know that can't be further upgraded. However the two machines are currently wirelessly interconnected. Will this be lost if the newer machine has a newer operating system?