External display issue with Macbook Pro - picture not clear

The other day I purchased a 24" Insignia LED 1080p tv with the intent of using it as an external display for my Macbook pro (purchased in spring of 2010). When I hooked up the tv to my MBP i noticed that the picture displayed on the tv is rather grainy/pixely and is not crisp or clear, as one would expect it to be. I currently have it hooked up to a new hdmi cord using a Rocketfish mini display port to HDMI adapter. I've attempted changing resolutions, mirroring and unmirroring displays, and even text smoothing. Has anyone encountered an issue like this before with an external display? Any solutions or ideas? Thanks!