SSRS 2008 Report toggling between images for various field values
You can use expressions for this type of conditional work. To do this click on the image and select the properties tab in BIDS. Find the expression button (fx) and click it. Enter something like the below to get what you want:


  =Iif(Fields!Gender.Value = "Female", "Female.jpg", "Male.jpg")


This is assuming that you have have set up the images to be available as global resources to your report. If not, replace the image names with the paths to the images etc...

A good reference for expressions is below:

http://msdn.microsoft.com/en-us/library/ms157328.aspx

I hope this helps you.