P-P,
Of course Kodachrome scans suck...Kodachrome is probably the single most-difficult color slide film for modern scanners...Kodachromes scan like crap...just like Tri-X scans like crap...virtually any E-6 films will scan better than Kodachrome....I used to shoot Kodachrome 64 and Kodachrome 64 Professional by the brick back in the 1980's...it projects beautifully and has almost unmatched DARK storage life, but it fades rather rapidly when actually projected, making E-6 slide films a better choice for projecting frequently, or for long-term continuous slide shows that run on a loop setup. I have scanned quite a few Kodachromes,and most scanners do a very horrible job with it, but last week there appeared a review for the Plustek 7600 film scanner on the Luminous Landscape web site; that scanner is apparently,one of the absolute best scanners for handling Kodachrome originals and converting them to excellent scans, so it would be very worth checking into that model of scanner.
By the bye, Steve McCurry, of National Geographic and "Afghan Girl" fame was given the very last roll of Kodachome that Kodak made, and McCurry recently shot it. National Geographic is going to do a special on "the Last Roll" next spring. Read more about the end of Kodachrome here.
The Online Photographer: The Last Roll