Yes I know ... that's as good as my scanner would do for de-screening.

Why don't you descreen them manually with Photoshop? It gives a better result.

Because my scanner does a better job than I can in photoshop. Photoshop might do a better job but not in my hands.

NeatImage is pretty straightforward.

If you're really photoshopphobic, you can just post unfiltered 600 DPI PNGs and let other people do the filtering. They'll be pretty huge files (expect 30-50 megs) so it'll probably strain your upload, but good filtering makes a huge difference ...