Calibre was a poor example. Processing eBooks is a trivial task for any PC. Another program that I use is Handbrake to transcode video files. It is also available in 32bit or 64bit. I downloaded the latest version of each and did a test. I transcoded a 4GB avi mpeg-2 file to an mp4 file. I used the default settings for both tests. The resulting mp4 was 400MB. It took 11m 25s for the 32bit version and 10m 57s for the 64bit version. My PC is a 5 year old Toshiba Portege notebook with an i5 processor and 4GB of RAM. OS is Win 7 64bit. The 4GB of RAM is certainly a limiting factor, but I would of thought there would have been a bigger difference.