I'm dealing with the same situation.
With Photoshop Elements I use to scan a picture at 300 dpi, save as PDF file, jpg compression medium low
quality and alway got files under 5 Mb, even lower than that. Colour or black and white pictures.
Now with Photoshop Elements 8.0 did the usual procedure but the pdf are huge, larger than 8 Mb, even more
than 10 Mb !
Am I missing any detail in settings program, perhaps ?
Thanks for any suggestions.