HDMI PC connection to LCD

Hello, I have a Dell PC with an HDMI port - (OS is Windows Vista) and I connected an HDMI cable from my PC to my Sony Bravia LCD TV so I can use the TV as a computer monitor. All I see is a blue screen.

I also tried to connect the PC HDMI to my Onkyo receiver and same issue. I tried every input but it didn't work.

Do I have to change any settings on my PC so the PC recogizes the Sony LCD?

Thank you