Framer, unfortunatly I haven't got supporting sources handy so feel free to dispute this, but the idea of Moscow being saved by regiments of Siberians who were immune to the cold is largely an invention of German propaganda (along with the Russian soldier being closer to nature), supported by the testimony of disgruntled German officers. The most damning evidence against the 'Siberians' thesis was that Soviet divisions were not organised along regional lines but instead troops from all over were grouped together at depots and sent to the front. Regiments did often recieve honourific titles (such as the 2nd Guards 'Taman' rifle division) named after sites of their victories but there were rarely regional distinctions. The exception of course is the locally raised 'volunteer' regiments, effectively units of men and women of service age drafted in 1941, given uniforms and the minimum of training before being sent to support more seasoned units. Thus in your average soviet division you might see ukranians, latvians, uzbeks, siberians and so on.

Not really important to the 'what if' but something worth remembering about the makeup of the Soviet military.

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There's no honorable way to kill, no gentle way to destroy. There is nothing good in war. Except its ending.