Sorry, I was in a bit of a mood last night when I posted my original response. I also thought that after I typed "It's where all the other gadgets are" that I actually put instructions on where they would be.
Anyway, it's supposed to be there if you right-click the desktop and click on Desktop Gadgets or whatever it's called (I can't remember, I work on XP, Vista, 7, server 2003, server 2008, and SBS versions 2003, 2008, and now 2011 all day) and they're all a little different with their wording, and all I have at home which is where I'm at now is Win XP and linux.
Sorry for being "harsh". Again, it should be where the rest of them are, and I've read from other posts that if it's not there, a clean install should get it there. Which means download the uninstall utility from the avast website, uninstall avast, reboot into safe mode, run the uninstall utility, reboot, then install avast again.
Hope that helps.