I have a PC and have never had any problems. You can use it year after year just by changing the preferences. In fact, you could use it for other dates as well. Very simple to use.
I dl'd and it's work great for me. And I am using windows too. You right click on it and click on Widget preferences, you can change the date. I would love to see more options. My son loves this to death. I vote for a stocking, reindeer, or santa!
Sorry everyone for not updating this! Been busy...I am converting this to Windows Gadget too so people can use it on the vista sidebar. I've updated it for 2007 so you can use it now for this holiday season even tho we're almost half way there! I do want to put in time zones to make it user friendly, and to customize the picture so you don't always have the ornament, you could do a tree or stocking or something. Hope you all have a great holiday! Thanks for checking this widget out!