I figured out, that a kernel panic, which was produced after install, could solved for me using this guide. http://osx86.wikidot.com/known-issues#toc1
So I removed the Geforce/NV-Kexts and I could boot up. But without the NVinject-drivers the whole aqua-UI was lame and lazy, so I tried to reinstall the NVinject drivers manually. But after reboot the same kernel panic again (even tried all boot switches).
What can I do, to make the drivers work, or what could have caused this issue?

Might help to tell us what graphics card you are using, what version of leopard?

Ok, you're right. i installed the latest release (10.5.2 rev2) and i have a geforce 7600 gs on agp-port running.
But just now, I recognized, that my graphics card is detected in system information under leopard as PCI connected!?
Any ideas?

I can't give you the info myself as I'm using pci, but I'm sure I've read issues about agp either on this forum or insanelymac, if you browse around I'm sure you'll find the info is here somewhere

When did you inject the Nvidia drivers, before or after the installation?

Ah, welcome to the club try "leo_vid_kexts.zip" from rapidshare. That might solve your problem. Might not.

I've got GeforceGo 7600 btw. It seems that 7600 series are troublesome.

7600's are troublesome. Sorry to say that, but its simply true.

@ WinLinMac01, I think, you are talking about 7950 not 7600. This card is absollutly supported, i have 3x7600, 1x7300 1x7950, and all are working perfect. Another thing is the laptop version (GO) or AGP version. Go here and take a look.

I have a GeForce 7600 GT and it's truly an out of the box experience I love it!

@farcaller, are you using nvinjectgo.kext and the correct device ID for your card?