Duh, thats fairly obvious actually isn't it! I got a bit confused by the options in Japanese, but I still should have realised really. Anyway even "zoomed in" on an area of the image, at 25 by 30 my D40s delivered excellent quality- no "lack of megapixels" complex here!
25 by 30 seems a nice size for framed photographs- it works with a couple of the ones I had done, but with the others my composition has obviously been destroyed by the cutting of megapixels to suit the ratio. Damn it.
As for matte (spelt correctly this time) vs gloss, I'll go for matte next time and compare- it certainly appears to have the benefits of no glare and no smudging.