If you're missing or accidentally deleted the Boot Camp Assistant from Macintosh HD/Applications/Utilities, you can reinstall it from your Leopard disc. With either the upgrade or install disc that came with the system inserted, go to the Go menu and select Go To Folder. Type /Volumes/Mac OS X Install DVD/System/Installation/Packages/ into the path if you have the retail Leopard disc or /Volumes/Mac OS X Install Disc 1/System/Installation/Packages for a disc that came with the computer. Double click BootCamp.pkg and you're good to go.