Brand new tv looks grainy?

I just bought a brand new 37" LCD Vizion tv... Im using an antenna for now because im waiting to get the cable all hooked up and ive noticed 1 channel comes in perfect but all the other ones look like crap.. also i hooked up my ps3 and the picture is all grainy.. i was told that the hdmi cables would fix this... show more I just bought a brand new 37" LCD Vizion tv... Im using an antenna for now because im waiting to get the cable all hooked up and ive noticed 1 channel comes in perfect but all the other ones look like crap.. also i hooked up my ps3 and the picture is all grainy.. i was told that the hdmi cables would fix this but im not sure about watching tv.. anyone have any ideas?
Update: im on my ps3 and its on 480i doesnt give me an option to change that but hdmi cables fix that right?
Update 2: The hd channel looks amazing and the DT is good but the rest suck. thats because the antenna right?
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