Help with XML and Flash image gallery

Ive done the XML photo gallery tutorial and its just what i need. This is the tute im talking about:

the only problem is, my client doesnt know how to resize images. Is there a way i can get larger images to resize to fit the gallery size? Would this require some PHP?
Im very sorry of this has been discussed before but ive searched and searched and havent found a difinitive answer. Could some possibly post some source files i could take a look at?
thank you,