Just a heads up on Paint... The default bmp format is 24-bit, which has no alpha channel. 32-bit and DXT3 both incorporate alpha channels, making them compatible with FS9 as a texture. The only place I know of in FS that will accept a 24-bit file is in the 2D panel.
Sorry if I misled you on the format saves lemmonadedrinker. I am extremeley green at painting and the understanding of it. I am also using the plane in FSX. There are many more here in this forum that are way more qualified to give you and I both pointers about the do's and don'ts of painting FS models.