Whether these features are worth the extra cash is up to you. What's included in the Professional edition that you won't find in the free Home version are push updates (meaning that Alwil will deploy high-priority changes to your program rather than you requesting them or waiting for the next automatic update), a script blocker (a heuristic to analyze javascript and Active X), custom tasks (such as setting Avast to run whenever your screensaver kicks in), a scheduler, and a command-line scanner (for initiating scans at a C: prompt, for example).
