Can nobody help me?

I created one partition with the OS X Installation Disc. Next I installed OS X. However, when I try to install Windows 7 on the other free HD drive space is says that it isn't able to install, as the partiton table or something similar is not correct.

Installing Windows 7 and then OS X doesn't work either!

I also tried to create the partitions in Ubuntu, but that also didn't help....