I have experimented with different resolutions on my PC which I use in conjunction with an LCD TV. Have been running my PC through an LCD TV for over a year now.
I have found forcing 720p on my video card is best.
While I don't think you will have that option, you should start at 1280 x 720 on the TV. I would recommend experimenting with all options available between 1280x720 and 1366x768 to see which one will fill the screen and also give you the best appearance particularly when you have text on the screen.
In case you don't know where to do this: Open System Preferences - Displays
The Display box will actually be two separate boxes, one on your MacBook and one on the TV. Move to the box on the TV to make your adjustments.
I have not yet been successful at getting text to look as good on either one of my LCD screens from my MBP (and OS X) as I can on my desktop PC (XP). Though admittedly have only tried 2 or 3 times. MS has their ClearType which dramatically improves appearance with an LCD TV screen. Have not found anything like this for the Mac yet. Have posed the question on a couple of forums with no response in either one.
Just as an FYI, primarily for those out looking for a new TV.
True 1080 i or p = 1920 x 1080
True 720p = 1280 x 720; as you can see 1366 x 768 is only barely above true 720 specs
Most all LCD TV's native resolution is 1366 x 768. These are commonly referred to as 720p TV's. Any salesman calling this a 1080 set is misleading you. Many salesmen mistakenly call a set that will accept a 1080 signal a 1080 set. This is not just incorrect but is flat wrong and you have a salesman that knows nothing of TV's or is intentionally misleading you. It will accept this signal, but then down converts it to it's native resolution. Always ask what the native resolution is when shopping. EDTV's will also accept 720p and 1080i signals but down converts them to 480p. This same salesman would be quick to point out that is not a 1080 TV.
Most LCD HD TV's will accept 480i, 480p, 720p and 1080i signals. In the last year with the advent of HD DVD and Blu-Ray we are now seeing some that will also accept 1080p signals and this model year even some true 1080p (1920 x 1080) sets. There are also many pretenders out there that have managed to produce LCD's somewhere between the 720 and 1080 resolutions and calling them 1080. Have seen one manufacturer with a 1366 x 1080 call their TV a 1080. Wouldn't buy it except for a spare and if it was dirt cheap.