Tips on using Power to Choose?

Hi there. I’m moving to the Spring/Woodlands area and I’m trying to pick an electricity provider. I see the power to choose website but I don’t want to be naive. My realtor told me that Direct, Reliant, TXU and Blue Mountain are popular. But I don’t see any of them amongst the cheapest providers. How is this website ideally used? Intuitively, I want to go with the cheapest provider possible but something tells me there might be more to the story. What’s your experience? What’s a good rate for this time of year?