try rendering the files before playback. I have the same problem on my sony workstation, when i add some effects, the render takes a little while for some hardcore effects, but once you render it plays perfect. Premiere is a synthetic real-time playback editor, which saves you from rendering everytime, but thats only for basic stuff. Also if you dont want to have to render, right click on the video in the monitor, and click quality, and use draft, because that might ease it up a bit. But dont quote me on that, im no expert!

Ryan

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Mac G5 workstation with 4 gigs of ram, 4x250 gig drives in raid 5. High availability cluster server running centos for a server. 2xCanon GL2 cameras.

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