Every time I repaint an aircraft, I load up FS, start flying an then I notice the textures are blurry

Now I know about using DXTBmp, I open the texure in that first, load it into PSP 8 and start repainting.
When I've finished the textures look great, reload in DXT after editing and save.
I've just downloaded all the repainting tutes available here, but was wondering if anyone could help too

Cheers,
Carl