Vista Problem?

[LogiK]

Alrighty, I just installed Windows Vista. Everything was working fine but about an hour into use my monitor srambled and I had to shut it down. I turned it back on and my monitor is getting no output. I checked my specs and they are more than compatible with Windows Vista. Anyhow I have had these problems before but usually I would wait a minute or two and turn my computer back on and it would get output, but now it seems to reveive nothing. I turn on the comp and the monitor and all I get is "No Input Signal". Than it goes to powersave. It has been a full day with no progress so I come to you guys. Please help me out, I don't wannt buy computer parts that are unneeded if any.
2g Ram
256 Graphics(Nvidia GeForce 6600 GT)
Amd 64 Processor

 

[nVdia]

Is your externel power plug in plugged in on your GFX card?

 

[Phrantic]

Open up your case and see if your videocard fan starts spinning when you power the pc up.