Carlos alloatti has just published a new and very interesting article about image formats, I strongly recommend people to have a look at this new great work from Carlos.
http://www.ctl32.com.ar/articles/what_is_the_best_image_format_for_VFP.asp
Also, don't miss to visit his CTL32 site, full of really cool and useful classes:
http://www.ctl32.com.ar