XP Pro SP3 - Was using Avira Free, decided to give MSFT's free AV a try. Turned off Avira's on demand feature, downloaded and installed MSE. It took a long time ( 2+ hours) to install and then download the definitions. Took 9 hours to complete the first full scan - 40GB internal HD (< 50% full) and 160 GB external HDD (< 40% full). Is this SOP for MSE? I thought MSE auto-updated the definitions, but no change in definition version date since install, 7 days ago. Can not find a switch to turn auto-update on (or off). Did I misunderstand? Machine's operations are definitly slower with MSE versus Avira. Is this normal? Is there an MSE-specific forum/newsgroup?