Don't get the Powerbook G4....<Br /><br />I would suggest either the new Mac Mini or the PowerMac G5. I would personally choose the Mac Mini since I don't know which G5 you're talking about. If it's a single or dual core, I wouldn't get it, but a Quad core would be pretty good for video encoding.<br /><Br />I would still choose the Mac Mini, because I would be able to run the latest OS, and it has the latest, most modern processor of your choices. Also, the Mac Mini would save you more money than a PowerMac G5, because the Mac Mini uses less power.<br /><br />The Mac Mini does support dual displays. It has an HDMI port and a Thunderbolt port. You will probably have to buy adapters. Also, you can use Mini DisplayPort to VGA/DVI converters with Thunderbolt.