i do many many video and audio transcoding, extracting, pasting, mixing, video editing. i bought my first dual core platform to let me use virtualbox, web browse and transcoding etc. at the same time. it was an amd 3ghz with 1mb L2 per core, it was very fast compared to some of my other machines 1/3 faster doing side by side ripping transcoding tests. although i could run the vbox and transcode at the same time i could not say rip a dvd, transcode a full sized avi to psp (small screen mp4) and run the vbox at the same time. so i went for a quad. 2.3ghz 1mb L2, 2mb L3. disappointed much slower. could not run the vbox, transcode and rip at the same time. upon further investigation i discovered that some software, will use a seperate core for each instance running for example i could transcode 3 different files with one program opening a different instance for each file and it appeared the cpu's were being used seperately using gkrellem, but when i started say an instance of vbox it did not appear to get directed to its own core as the other running programs seemed to be but mixed into an already running one. another thing i noticed is that some software would use both cores but only a 50 50 type of split was happening for instance one extractor program would have core 0 at 78% and core 1 would be at 22% then quickly core 1 would be at say 43% and core 0 would drop respectivly to 57%. some software seemed to work much better with the multi core setup than others. so i would have to agree with coonhunter that it depends a lot on the software.