Digital BW, The Print

I assumed that 360 ppi was the correct resolution for my own inkjet 
printing and for discs to send to an offset printer for inclusion in a 
book. He says they prefer 400-600 ppi for best results. (We already 
clarified the ppi/dpi issue). I would appreciate advice from those 
experienced in dealing with offset printing houses. Should I start 
saving my images at higher res? I couldn't exist without this forum!  
Thanks so much
              Arlene
arlenelove3@...
www.arlenelove.com