Microsoft have announced that Halo 3 will start shipping on Tuesday the 25th of September, the European release will be Wesnesday the 26th of September. So I've released a Vista sidebar gadget for Halo 3.

Halo 3 countdown sidebar gadget

It's pretty simple, it countdowns to the release date. There's two versions for each region North America and Europe (126KB), download from Microsoft's gadget gallery North America and Europe.