I would also recommend Wings 3D (
www.wings3d.org) for making ship models; it has a UV texture mapping plugin (what you need to make the texture bitmaps for the models
) and exports to .3ds, which is easily converted to .x (just look on Google for a program called 3dsconv.exe). Wings has a TON of mesh manipulation commands - I made the saucer section of the Enterprise in just a few minutes by creating a cylinder and repeatedly insetting and extruding faces on either side!
Now you say you can make your texture files ANY size? That's news to me... looks like ships might start coming in "good graphics card" and "crappy graphics card" Versions!