Snow Tires for 2010 Prius

If I install snow tires (Michelin X-Ice) will the miles per gallon decrease by much? Any other suggestions for brands of snow tires?

Oh good, one of my favorite topics: snow tires

Goodyear Eur-Winter Tire-UltraGrip 500

With my '04, putting on the studded Goodyear Nordic winter tires - this is the same tire as the Goodyear Ultra Grip 500 sold in the EU - I noticed a 2-4 mpg loss, depending on conditions.

As you will notice, the Nordic/Ultra Grip 500 is a *very* aggressive winter tire. But if you end up sliding into a ditch or guardrail somewhere in BFE, you're probably be getting 0 mpg

I just put on my snows, Green Diamond Tire, and it looks like my MPG is dropping about 10% (5mpg or so) without even actually going through any snow yet :-(

Ouch, I was hoping that wouldn't be the case. I will probably be putting on mine within a week so we will see.