Despite being built with the aging Unreal Engine 3, Thief touts some cutting edge rendering techniques that have put the game on our radar. Thief's built-in benchmark appears to do a good job of demonstrating a worst-case performance scenario, so if your system can average 60fps in the benchmark you should enjoy perfectly smooth gameplay from start to finish.
There was a time when the size of a gaming notebook didn't matter so much. Three or four years ago a portable gaming rig that was nearly two inches thick and weighed close to ten pounds was an impressive thing. Pull one of those beasts out at a crowded coffee house and the other customers knew you weren't about to pull up a spreadsheet.