Actually I think someone has done this ("go back in time to fight in WW2"-thing), and I got evidence: http://en.wikipedia.org/wiki/Jack_Churchill
I mean, he fought with SWORD and BOW & ARROW in WW2, played bagpipes and got captured by Germans, survived, then later on became a surfer
Anyways, yes, I'd go back in time to fight in WW2, AS LONG AS I also won't be captured by the Nazis. One thing is fighting in WW2, but being captured and sent to one of the camps or something like that? No thanks.
And hey, fighting on the front lines in WW2 would actually give my life some deeper meaning, as I can't say I've accomplished much otherwise