Crucial all the way baby! Don't bother with the mumbojumbo RAM. Don't pay much over $100 for Crucial RAM as you can get it for under $100 shipped most of the time. Oddly, some places charge $1,000 for the exact same product so it will initially look confusing. Quite a profit margin though
They key thing with RAM is (a) does it work when you get it, and (b) does it come with a lifetime warranty from a company that will be around if should have a problem two or three years down the road.
With Crucial, I have no question that both will be true; and if I were to get a bad stick, they'd make it right very quickly.
I've never heard of "Qimonda", so unless you're outside the US and this company is a well known company with a long history of good service, I would stay away.