Try this:
Download Windows Installer SDK.
In it you will find a Orca.msi. install it.
With explorer browse to C:\Program Files\Microsoft Visual Studio 8\Common7\Tools\Deployment\VsdDialogs.
There you will find a subfolder for most cultures.
Go to the culture subfolder you're using.
Open VsdUserInterface.wim with Orca.
In the binary table you'll find a row with name DefBannerBitmap.
Double click [Binary Data] to select your own banner image file (jpg or bmp, not gif). It has to have a width of 500 pixels and a height of 70 pixels.
Store the VsdUserInterface.wim.
Build the setup projects again with having the BannerBitmap property refering to Default.