Buy a battery backup for your 360

[FTICRMS]

Seriously. They are less than $100 at electronics stores.

I've got two of them - one to plug my consoles into and one for the TV. They aren't really big but they'll give me enough time to save my game when the power goes out.

And no, I didn't just get them for Be***eled! The power is really flaky on my block. Every time a squirrel runs down a power line we get a hiccup. I learned not to set the clocks long ago.

[Borg561]

Good advice, and not just to keep you from having to restart Endless mode should the power go out while you're playing. I've been using a UPS for 4-5 years now. Currently have three of them. One for my main server and monitor, one for my other server and desktop, and one for my 360 and tv. Couple other items plugged into the various other ports (phone, speakers, router, etc).