Dual Channel (simple question)

Hi, noob here. My question is simple (yet difficult to answer through google): when you go dual channel, your total RAM is reduced to half? For example, I install two 1GB sticks (total = 2GB)in my PC, so when I run them at dual channel I get only get 1GB of available RAM with double the bandwidth, as opposed to 2GB at single channel?

OP: It's not supposed to reduce memory by half, but I do remember putting in 2 512MB sticks of PC3200 (same brand, latency) in my dad's (dual channel capable) computer and it showed up only as 512MB. While it could have been a fluke or it's possible there was some other factor involved that I don't remember, I never could get it to work properly IIRC.