Always use the LCD monitor at its native resolution, in this case 1440 x 990, as it is the only resolution where one physical pixel corresponds to a picture pixel your computer is generating. If you go over that resolution the monitor will have to recalculate and fit the higher res into what is available (i.e. 1440 x 990) usually resulting in a worse quality picture. If you go below the native resolution you have two options. Firstly, you can opt to show the lower resolution using a full monitor screen. This again will result in recalculation and very likely in lower quality picture. Second option is better as it will use exactly one physical pixel per virtual pixel but the whole picture will not cover the whole screen, so you'll have high quality sharp picture but unused parts of the screen will be black.
Barney
Barney