hmm.. prehaps it needs to load a different version of bootmgr? That should've worked a treat...
Ok, new plan: Enable viewing of hidden files/folders and protected OS files in folder options. Locate bootmgr that should be on your active partition at the top level of it. Go ahead and rename this file, to say something like "bootmgr.old" so its still there but it won't be used when you boot the computer. Now boot from your Vista DVD again, select your language, and do startup repair.