Hi, I have a 2007 13" MacBook which I use to drive an external video projector via a mini-DVI to HDMI adapter (external video monitor set to 1080p@24Hz). It manages 1080p, just barely, with some hiccups on complex material. But the signal itself is a nice, clean (and pretty) 1080p. I thought that upgrading from Leopard to Snow Leopard, with a clean (formatted) install, would somehow get rid of some junk background processes and make the machine run a bit smoother. However, since installing SL, performance in 1080p is even worse than it was the video has a deal-breaking "strobe" effect (i.e. the video updates only every 2nd or 3rd frame). Mirroring the display instead of using a secondary monitor plays smoothly, but then of course I don't get 1080p. What could possibly be the cause of this? Is SL a downgrade in terms of performance with 2007 machines? Can anything be done with the graphics subsystem to make it run better? Thanks for your help.