How about the Minolta Dimage Scan Elite 5400, I replaced my on Nikon LS20 with one last week excellent results. (Does not appear to work with Vuescan though).
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http://www.minoltaeurope.com/pe/digital_photography.html>
On paper it has a better spec than Nikons LS40 5400 dpi optical 16bit colour depth Digital ICE and both USB 2.0/1.1 and Firewire interface. It is probably equivalent to the LS4000 ED for about £400 less.