A US-German Alliance is improbable as is a Polish Russian one. A more likely alignment is a US-Polish Alignment vs a German-Russian one. I don't think Poland would want Vladimir Putin or his successor as their new "Czar".
I don't think the US would support Germany invading Poland, especially since Germany did not support the US in the Iraq War and actively campaigned against it. Feelings are sill likely to be raw in 2010, and I don't think the US considers Germany to be a good ally anymore, it is certainly not going to support an act of agression on Germany's part.
How exactly would you get Russia into the War? The most obvious way would be for Russia to invade one of the former Soviet Repubics, such as Latvia or the Ukraine, this would have to occur as a backdrop to the Second Korean War before it went nuclear and became World War III.
Now how to get Poland on Russia's side?
If Russia invades Latvia, Poland is going to feel threatened by Russian Troops. Poland was once part of Russia you know, an unwilling part. If Poland sides with Russia and thinks Putin is a great leader and their leader too, then what your describing is a very Unpolish Poland. I do not recognize this country at all, and my wife is Polish, if it can undergo such a radical reversal in politics in a mere 4 years. That's right, 2010 is only 4 years from now, I wouldn't be surprised if Vladimir Putin is still running things, or is pulling strings from behind the curtain as his appointed protege appears to run things to stay within the Russian Constitution.
My scenario doesn't include the participation of Russia and it doesn't have a European front, a more accurate name for the conflict would be the Pacific War. Europe probably stays out of it, the action occurs over the Pacific between the United States and China. There are not alot of European troops in Asia right now, not in Japan, not in Korea. So basically it is only half of World War III. Missiles fly and misslions get killed, but Europe only gets secondary effects from all this. That's a pretty strange Situation for Europe to be in, I'll admit, but Europe has been trending isolationist as of late, the number of entanglements that would drag them into a world wide conflict are getting fewer and fewer. I think once missile start flying and cities begin to be destroyed, I think Putin will lose his appitite for reconquering the old USSR territory very quick. I don't think the conventional part of the Second Korean War would last long enough for putin to hatch his plans, and remember each side gets involved thinking the other would back down rather than use nuclear weapons, once it becomes clear that this is wrong, I don't think Russia would want to test America's resolve at this Juncture.
I think a more likely situation is Russia just sitting on the sidelines waiting for the USA and China to destroy each other without taking sides in this conflict. The European Union would find a way to remain neutral as well. There may be a local Arab/Israeli conflict, but if Israel goes nuclear, I don't think Europe would want to risk any of that by siding with their Arab friends. Europe would stay neutral.