As far as converting lightwave to .x use Deep exploration if you can (not sure how much it is I have to take my files round a friends house for conversion). but its as simple as opening the file and saving it again.
although milkshape is capable of converting it too(you have to export from lightwave as a .lwo version 5 file - so you lose all your saved textures if you use anything higher) and then export from milkshape as a dirct x file (.x). You'll either need to retexture in milkshape or something or declare your objects rgb values in DB or you'll get black objects.
*helpful hint if your using lightwave to model don't forget to triple your model (this if you don't know turns all the surfaces into triangles) this will stop your models looking incredibly deformed as my first few did.
Somewhere in the forums someone did mention the scale changeover rate from lightwave to DB. I think it was something like 1` lightwave meter to...oh rats I don't remember.. (I'll seee if I can find it and edit this post later.
'Ooh 'eck chief'...'crumbs'