First a couple of questions. What is you ultmate destination for the Pixs?

If it is for posting on the internet or for prints or for submission to magazines? Each destination will warrent a different answer.

For the internet:
Pictures destined for posting in articles on the inernet don't need to be large. With the lenses you have you could set up the camera at it's closest focusing distance, take numerous shots and crop them later for posting. With 12 megapixels at you command, a picture taken from 0.38M can be cropped and still have enough detail for the internet. The added bonus of doing it this way is that the depth of field is greater. Since you have the equipment, experiment and see if cropped photos give you what you want.

For print media (home use):
As for pictures printed in 4"x6" (100mm x 150mm) size, the same rules for the interent apply. I have sucsessfully printed photos froma 2 megapixel camera on 8"x10" (200mm x 600mm) and had it come out clear. Your existing equipment should be good enough for home use.

For Print media (magazines):
Though I have never submitted a photo to a magazine in digital format, the quality of the photo should be much higher. If you intend on taking a lot of macro photos, saving up and investing in a macro lens (not add on filters) may be your only recourse.

Style:
Photos taken very close to the model look different from photos taken at a distance and then cropped. If you want the picture to look like you were standing next to the real thing, you will need a macro lens to get close enough to achieve the same vanishing points. I wish I had an example to show you, but none are near to hand. If I can, I'll take some photos tonight and post them tomorrow.

I hope this helps. Have fun experimenting with your D40!

Aloha,
Val