Max,

It appears that you are using Pub 2003 and so read the article: Compress
graphics files to create smaller Web site files:
http://office.microsoft.com/en-us/assistance/HA011266301033.aspx

Also from David Bartosik's site, here are two articles you might find
helpful:
http://www.davidbartosik.com/2004/12/how-to-prepare-images-for-your-web.htm
and
http://www.davidbartosik.com/2004/12/how-to-prepare-images-for-your-web_25.h
tm

If you don't have an image editing application to optimize your images, here
are two freebies:
Picasa: http://picasa.google.com/index.html
and,
Irfanview: http://www.irfanview.com/

DavidF