Hi, just thought id let the community know that mavericks on my late 2007 imac with 4 gig memory, works very bad indeed, very sluggish and start-up times for proggies are almost double to what it used to be, even my mail (apple en outlook) are suffering, i know that it was a shot in the dark but i had to try it, and now ill be trying mountain lion, if that don't succeed its back to good old snow leopard 10.6.........hope this helps people who otherwise were going over to mavericks..........