Ok, so I have an Oct. '09 27inch i7 iMac (stock, 1tb hdd, 4gig ram) and a 15in MBP with core2duo 2.8 and 4gigs of ram. I want to upgrade my iMac to at least 8gigs of ram. I don't do a lot of heavy photo or music editing, but some, and I game a lot on it. It is actually running windows 7 64 all the time now with only about 120gigs devoted to the OS X partition. I have heard a lot of mixed things on whether or not the ram upgrade will help a lot with gaming, but I am planning on streaming and recording Starcraft 2 so I am sure the ram will help a lot with that. Now what I wanted to do is get at least 1 4gig ram stick so that at a later date I could stick that in to my MBP to get to 6 or 8 ram on that some time in the future (I'll probably get a new windows desktop in 12-18months since the graphics card is quite crappy on the iMac and I miss eSata, SSD, and USB 3.0). So I'll just be building a new desktop then and using the sexy sexy monitor of the iMac. I have no plans to upgrade my laptop anytime soon, I absolutely love it. I've heard that its best to add ram to the iMac in pairs, but how true/important is this? If I just get 1 stick of 4gig DDR3 1063 and put it in my iMac will it all work good? If not would getting 2 sticks of 4gigs each be a better option (though overkill). If in say 2 years though going from 4 to 8gigs on my MBP won't make much of a difference since I'm using it mostly as a browser, media player, and back up game machine, the safer route may just be the getting two more sticks of 2gig ram for the iMac. But I imagine by then the 4 gigs will make a difference with most programs (the laptop runs OS X of course, I love the operating system, just the drivers and lack of games on it kills it for my gaming sadly). I hope that wasn't too long winded and I got my point across. tl;dr one 4gig stick, two 4gig sticks, 2 2gig sticks for my iMac. PS: I am actually wondering what I can have running on the iMac while using it as the main display for another computer, is it easy to switch back and forth? Can I have them integrated somehow so I can have say browsers and media playing through the iMac and games through the PC?