Quick question, for my 52" Samsung LCD 1080p, should i put the settings on dish to 1080i, or would it be better in 720p?
Displays like your Samsung TV have converters in them that can accept one format and convert it to the display's native resolution. Likewise source devices like your receiver contain converters allowing them to output what ever resolution you need. If you run your video through an AV Receiver it too may contain a converter.
So, the choice of format settings can be both confusing and simple. Whatever settings you chose, the devices will figure it all out and give you a decent picture. However, if you are fussy, you might want to think about it more.
Not all converters are equal. If you have a device with a cheap converter, you might find you are better off not using it and letting a device with a better converter do the work.
As an example, I have a 720p DLP projector that is known to have an excellent format converter in it. My mid-range Denon AVR receiver has a cheap converter that can produce artifacts, so I have its converter disabled. My Blu-Ray player outputs 1080p, the Denon passes that along unchanged and the converters in the projector do the heavy lifting. I do the same with my Dish receiver.
You can rely on product reviews to tell you which devices can provide the best conversion, get all devices that work at the same resolution so conversion won't be necessary, or experiment to see what combination looks best.
In reality however we are talking about subtle effects. I'd guess most of us wouldn't see much difference between a bad set up and a great one.