but the bootloader is installed
X___x

take the DVD out, and make sure you have correctly modified the GUID bootloader (remember, you can always do it again). =)

yes thats sure. ive type in the stuff alway 3x but i dont works ((

it looks like the computer starts from windows or linux -> black screen an text but then -> boot disk failure please insert system disk and press enter

Did you select the correct Harddrive (On which you installed Leopard) in your BIOS to boot first?

Sorry to but in again but effigy, what did it say after you typed the dd if text?

i have 2 partions ->1. "MAC" (with leopard) -> 2. "WINDOWS" (without anything)
after i typed in the dd if text it say: "Permission denied"

i just had one harddrive (160 GB)

You need to unmount every partition on that hard drive, I found most reliable way is to do it with disk util

@_@ really? hehe