Holocaust denial

I have been reading a lot of stuff recently, some of which has disturbed me.  There are a lot of people out there who say the Holocaust, that horrible time in history they taught us about in school never really happened the way they say it did. 

They cite how there's no way camps like auschewits(sp?) had the capacity to eliminate as many people as they said were held there.  They talk about how zyklon-b wasn't really powerful enough to kill anyone, and those showers apparently outfitted with this chemical were actually used for a delousing procedure.  They talk about how it doesn't make any sense to trick people into going to their death when you've already got them in your custody.

I don't know man; holocaust deniers seem to have information to back them up, all kinds of evidence, to which the holocaust sympathizers only have name calling and questioning the motives of those who deny it.  I am someone who really would like to believe that the holocaust happened, if only so that I can believe there isn't a vast conspiracy behind it.  So, any holocaust sympathizers with a good rebuttal to what they're saying?

Another thing few people ever bring up that people have been posting on here. Above the Aushwitz enterance (or one concentration camp) there are the words arbeit macht frei, which means "Work makes you free." Jewish labor was a huge boon to the nazis. The nazis provided the inmates with medical care, dentistry, soccer fields, an ochestra building, and a swimming pool and they regularly fumigated for typhus which was carried by lice. They worried about keeping the Jews alive because the JEWS WERE MAKING THEM MONEY. The concentration camp labor was USEFUL. They wanted MORE laborers, NOT FEWER.

The people for the holocaust don't even mention this. It flies in the face of logic and common sense.