No you don't need to flash the eMMC, it you're at the flasher dos box and it says "no suitable device found. Waiting" it means it hasn't detected your N900 connected to your PC. It could be due to windows drivers trying to install and therefore blocking the installation. I had exact this same problem so booted into a live version of ubuntu 10.4 netbook and it worked first time a treat. ubuntu FTW!