imaji,
I'm running the MAC version and my books are typically 0.3 - 0.7Mb.
I must admit I tried the sync and then stopped it as it was trying to do All the books in my library including ones it can't read (Mobi etc) as I had pointed it to my Calibre flies.
(I suppose that's what sync means,
)
As Calibre doesn't work with Snow Leopard on the MAC yet I'll be trying the Sony Software a bit more often in the near future though so I'll then be in a better position to assess all it's "quirks"