CloneDVD can be used to create an identical copy of a DVD, which is helpful to create 4.7 GB copies of a 9 GB DVD9. Since this requires some processing power, the CPU plays a major role. One Phenom core is noticeably faster than one Athlon 64 X2 core here.
The H.264 encoder by Mainconcept is a performance hog: you'll save a quarter of your time by running it on a single Phenom core when compared to a single Athlon 64 X2 core.
Studio 11 benefits a bit by Phenom's improved core.
The time savings when transcoding MPEG-2 video into DivX is more than noticeable.
Video transcoding into XviD is also much faster on a Phenom core than on an Athlon 64 X2.