Hello all I am open to suggestions concerning my iMac 5,2 (late 2006), 17", C2D, 1.83 GHz. MA710LL I bought it used and someone had OSX 10.7 Lion, on it. I noticed it runs okay, but is very sluggish when viewing (web) videos in a full screen mode, or when two web sites are open. Videos on a Small screen are fine, but full screen, it gets choppy at times and poorly syncs sound with video. The graphics card GM950 is just not the best, I know. But it is what it is. I am not an expert by far, but I wonder if what is slowing it down is running Lion, with only 2 GB of RAM. It is my understanding after researching this, that unlike the 2.0 Ghz model, I cannot upgrade the RAM above 2 GB (per Apple, OWC, Crucial, and many many posts by owners of that model). It definitely is limited to that maximum amount of memory. So if that's the case that I cannot upgrade the RAM any further, perhaps the unit is meant to run it's original Leopard or even Snow Leopard (I have an original install disc from my mac mini). Perhaps Lion is not using the existing RAM efficiently. This is all conjecture based upon my limited knowledge. So to finally get to the questions: -Anyone have experience with this situation, of running limited RAM on a higher resource-using operating system like Lion? -Does anyone have a response or experience, concerning running Leopard or Snow Leopard, on 2 GB, on a unit with this particular configuration? -Any opinion on my "rolling back" the OS, in order to get a better performing machine? Or am I just wasting my efforts by doing that. Comments, suggestions, opinions are all welcomed. Thanks in advance DonCarlos -Oh BTW, I already have cloned this system to an external, so I have no issue with "rolling it back", since I can bring it back to present state if needed. As I mentioned before I have a SL install disc, and too I have a Lion installation on USB, from my Mac Mini days. And yes, I do have the capability of running from a FW external a version of SL or Leopard, but I would just rather run the appropriate OSX internally in the iMac, if that improves performance.