OK, once you have created your installer using the appliation builder. Launch Orca and open that .msi file you created. The defalut name is install.msi. On the left is a coloum called Tables. There is a selection called "Binary", that is where your pictures are. The top16 and side16 are the ones you want to replace. Doubke click the [Binary Data] and give the path to your picture you want to replace, the "Write binanry to filename" puts your picture into the msi file. My pictures I left as jpg and it accepted it fine. This is just one of many items you can change in your msi. I found a link of Microsofts web page, http://support.microsoft.com/kb/255905/EN-US/ It might be worth a shot. One thing to remember, you need to have your picture attribultes match the size of the box, or it will look funny.
Ben