I also use the Minolta Scan Dual II and I'm extremely satisfied with it. When I bought it I also looked at the Hewlett-Packard S20, but I came to the conclusion that the Scan Dual II is the better choice (don't flame me, Ivi
) simply because the S20 is older.
As a consequence, the S20 is now available for EUR 350 or even less, while the Scan Dual II is between EUR 400 and EUR 500. Remember, both are excellent scanners for their money, so it's your choice.